Caesarea Maritima PDF Print E-mail
Written by Stephen Langfur
Article Index
Caesarea Maritima
The Theater
Hippodrome, Palace

The pool at Herod's palace in Caesarea MaritimaIn 22 BC Herod began building a harbor on the long, straight Mediterranean coast. For the site he chose a Hellenistic city called Strato's Tower, which Augustus had recently given him. It had no natural breakwaters, but Herod was not deterred. 

The project was ambitious, expensive and risky. The big harbors at Piraeus and Alexandria used natural protection, but Herod built his of hydraulic concrete. This had been done more than a century earlier at Cosa in Italy, for a distance of 150 meters into the sea. But Herod's southern breakwater, all artificial, curved a full 800 meters into the Mediterranean!

Caesarea harbor aerial

Local engineers had no experience building in water, and that of Roman engineers was limited to  smaller projects. The sea bottom, a few meters beneath the surface, consisted mainly of sand. When building on so huge a scale, how could you be sure that the sand wouldn't shift or that currents wouldn't undermine the breakwater? In fact, you couldn't be sure. Not long after the work was finished (some say at once, others say after a century), the parts built on sand began to sag and collapse. In addition, there was a fault line: structures built west of Herod's palace or the hippodrome have sunk by about 7 meters. The harbor was doomed from the start. 

To make concrete that hardens under water quickly (that is, in two months), the Romans used a volcanic ash from the area of Mt. Vesuvius called pozzolana, which has high levels of the crucial chemical compound for this purpose: silicate of alumina. They mixed it with regular sand, lime and gravel or pebbles. The Roman engineer Vitruvius specified a particular source of pozzolana in Book II, Chapter 6, of his Ten Books on Architecture, published two or three years before Herod began the project:

There is also a kind of powder which from natural causes produces astonishing results. It is found in the neighbourhood of Baiae and in the country belonging to the towns round about Mt. Vesuvius.

The last sentence turned out to be expensive. Using samples from ancient hydraulic concrete, scientists can trace the source, because each sample has a geological signature. Tests of the concrete beneath the water at Caesarea have shown that the pozzolana did indeed come from the area of Vesuvius. This means that thousands of tons were transported 1200 miles by sea - at enormous cost! Yet Herod had perfectly good pozzolana in his own back yard, in the area today called the Golan Heights, which Augustus had also awarded him. Why then go to the expense and trouble of importing it all from Italy? The reason, apparently, was the sentence of Vitruvius quoted above. "This conservatism," writes Christopher Brandon, "shows how little they understood the chemistry of the process and how much they relied on experience."

Was Herod's dream, as some have called it, Herod's folly?

The reviews are mixed at best. In its grand form, as said, the harbor lasted no more than a century, if that. (See Reinhardt and Raban, pp. 811-14.) The place continued to be used as a harbor, but not to the same extent. In fact, because of collapses near the entrance, it was positively dangerous to try and sail in. There is evidence of shipwrecks.

The Engineering Feat

Geology aside, the engineering feat was remarkable. Several techniques were used, all of them variations on the instructions of Vitruvius. At the western end of the northern breakwater, archaeologists have found the submerged remains of concrete blocks 15 x 11.5 meters and 2 m. high (Brandon, op. cit., p. 34). Each was cast within a prefabricated form. Each side of each form consisted of a double wall of planks. The space within the double wall was 9 inches across. Each double wall sat firmly in a large beam underneath, so that no water could get into that 9 inch hollow. The four watertight walls made the framework buoyant. Between the walls were beams and struts to keep it from bending, but the form had no bottom. Stones were heaped on the floor of the sea and the form was floated out to them. Once the divers had maneuvered it to its planned position, they filled the spaces of each double wall with pozzolana concrete, and the form sank into the rock bed. Then they piled more rocks against the sides to make sure it stayed put. This done, they filled the flooded inside of the form, layering the ingredients, including more pozzolana. "The concrete bonded to the rubble bedding, filling the voids and ensuring a solid bearing (Brandon, op. cit., p. 34)."    


Herod would have been under pressure, we shall see, to finish the harbor quickly. It took about ten years, which is considered fast. Archaeologist Avner Raban has suggested that the divers first laid island bases at strategic points, from which they could then build concurrently toward each other. They built barges that would serve as forms, each destined for one short voyage. The remains of three such barges have been studied. Here again is Brandon (p. 35): 

After being launched [the barges] were loaded with a layer of pozzolana-based concrete to a depth of 0.5 m. and allowed to set before being towed out to the site. Anchored in place, lighters and barges transferred more concrete into them to settle them onto the seabed... It would have required only 1.5 m. of fill to sink them....Rubble was piled against the sides to secure them in place and to protect them from being undercut.  

There are indications that in the shallow water near the shore (up to 2 meters), a simpler method was used: piles and overlapping planks were driven into the sandy sea bottom, making a rectangular form with enough of a seal to retain concrete. They followed this procedure form by form, step by step. 

So much for the techniques. But what was the thinking behind the decision to build this harbor and its adjoining city? We must consider Herod's motives and Rome's (for Herod could not have built so grand an affair without Roman approval and aid). 


Herod's motives

If Herod wanted to be a major player in the Mediterranean basin, he needed a harbor. He could have enlarged the one at Gaza, for Augustus had given it to him. But Gaza was near Alexandria. The latter was the second largest city in the classical world, a gateway from the Mediterranean to East Africa, Arabia and India; it boasted a magnificent harbor. To build another so nearby would have served little purpose. 

One function of a major harbor was to provide a safe place for ships to abide the winter (the turbulent winter weather made it unsafe to sail). Herod could justify building one harbor well to the north of Gaza, because the coast was long and straight, lacking sheltered places. There was Jaffa, of course, but its reefs were dangerous (and the population too Jewish for the Romanizing project Herod had in mind). The next good option to the north was Dor, but it lay outside his realm. He chose, therefore, the aforementioned Strato's Tower. It linked up nicely with the Jezreel Plain and the international trunk road, as well as with a major city he was rebuilding in the highlands, a kind of pagan capital, to be named Sebastia.  

Herod had other motives too. His main support came from Rome - specifically, from Augustus and his designated successor, Marcus Agrippa. He needed a reliable point of contact with Rome. Besides, he was immensely grateful to Augustus: although Herod had supported Antony during the civil war, Augustus had spared his life and restored his kingdom, adding to it. Herod built the harbor, therefore, in the form of two arms reaching out toward Rome with a temple where the head would be. He dedicated the temple to Augustus and Rome. He named the harbor Sebastos, which is Greek for Augustus.

In the satellite image below, you can see that the temple and the harbor formed a single complex, on a different axis from the rest of the city. The harbor was turned toward the calmer, northern side; its longer left breakwater bore the brunt of storms from the southwest; the entrance was in the northwest, and the temple was slightly turned toward it. Imagine you are coming in from a sea voyage. You think Augustus is behind you in Rome? But here is Augustus-Sebastos embracing and welcoming you.

Caesarea Harbor from satellite

Not only did Herod name the harbor after his protector, but he called the city Caesarea - it was the first of that name. Up in Sebastia he built yet another temple to the emperor. Augustus, Augustus, Augustus!  

But Herod's motives went beyond the desire to express his connection with Rome. He must have expected the harbor to make a profit. Since Gaza was in his power, perhaps he diverted the Nabataean traffic on the Petra-Gaza route this way. If so, the measure did not last beyond his death in 4 BC: Gaza was freed from Judaea and became directly answerable to Rome.

Detail of Caesarea Harbor

In the photo above, note the limits of the inner harbor. Here is how they look when we stand on the artificial platform that supported the temple:

Caesarea Inner Harbor

Roman motives
The rulers of classical cities were responsible to ensure sufficient grain at reasonable prices. At the time Sebastos was planned, in 23 or 22 BC, Rome, with a population nearing one million, had recently undergone famine. A reliable source of grain was needed. David Stockton writes:

The harsh truth was that if Rome could not keep the seas and secure the grain-supplies, the city would die. Even without pirates or wars to worry about, the prevailing winds meant that, while the corn-ships returning empty or in ballast from Ostia or Puteoli could sail straight to Alexandria in a fortnight or less, the full freighters heading from Egypt to Italy had to edge round the prevailing northerlies and take at least twice and sometimes three or four times as long over the journey. In the early second century A.D. the standard freighter engaged in the grain-trade could carry about 340 to 400 tons, and though we hear of giants of over 1,000 tons burthen there were many more (especially in earlier days) which could not manage as much as 100 tons. In the late Republic and early Empire Rome needed some 300,000 tons a year. Add that the seas were closed to long-distance shipping from early November to early March, and reckoned very dangerous from late September to late May, and it becomes easier to see how the management of the corn-supply, along with other complex jobs of a similarly 'non-political' character, helped inexorably to edge Rome away from the 'amateurism' of the Republic to the centralized control of the Principate.

The valley of the Nile, annexed by Rome to its empire in 30 BC, could serve as a major source of grain. Perhaps Sebastos was conceived as a station on the maritime grain route that started from Alexandria. But Augustus had a fleet of grain ships built, so large that they did not have to hug the coast. Adapting to summer's northwest winds, using a port tack, these huge ships could sail directly to the western tip of Cyprus, then to Asia Minor, then westward to Rome - a journey of 70 days. They bypassed Caesarea. For smaller grain freighters, however, the harbor would still have been useful.

There may have been another Roman motive as well. Augustus and Agrippa would have wanted a secure base for landing troops - a bridgehead - in the East. There was concern about Parthia, which had earlier defeated two Roman armies. Alexandria was too far south to meet a Parthian challenge. The next major point to the north was Antioch, at the bend where Asia Minor juts westward from Syria. Although the world's third largest city, superbly positioned to receive goods from the Euphrates, Antioch was extremely vulnerable. (The Parthians had already taken it, briefly, in 40 BC.) Augustus and Agrippa would not have considered it (or its partly silted harbor) secure enough for landing troops and training them. Caesarea was safer. It was farther from the Parthians than Antioch, and it was accessible from the East only by narrow mountain passes.

As things turned out, however, Augustus achieved a modus vivendi with the Parthians.

Finally, Augustus and Agrippa may have wanted to see whether such massive breakwaters could be built with hydraulic concrete, for they needed a harbor near Rome. The lesson proved valuable. Although Claudius and then Trajan used this concrete at Ostia, their principal approach was to dig the harbor out of the mainland. From the Roman point of view, Herod's Sebastos may have been an instructive experiment, showing them what not to try.

Caesarea did prove useful as a military base during the first great Jewish revolt against Rome (66-70 AD), when the Roman commander Vespasian trained his legions here. Likewise, the Emperor Hadrian had legions here during the Bar Kokhba revolt. The harbor was by then problematic, but the city itself had become the land's major Roman center, a status it kept until the Arab conquest in 640 AD.  

The harbor's significance for the people living here

To grasp the significance of the harbor at Caesarea for the people living in the land, we need to step back 40 years before Herod planned it. Another "Great," Pompey, had taken the land for Rome in 63 BC, ending a century of Jewish sovereignty. On the northern part of the King's Highway, the Romans replaced Jewish control with that of their own allies. The coastal cities on the Great Trunk Road, from Strato's Tower (later Caesarea) southward, were ultimately given to Herod. These two major roads formed a kind of pincers, by which Rome could rule the country.

Map showing Roman pincers

The Roman pincers were strengthened after Herod built this harbor, Sebastos. The local Jews and the Samaritans, living on the central mountain range, had been protected from the West by the long straight coast. Sebastos was like the opening of a wound in the side. Or to vary the metaphor, the Sebastos-Sebastia connection was like the thrust of a pagan dagger into the heart of the country. Soon after that connection was formed, some 93 Roman settlements sprang up in the (till then) lightly inhabited Sharon Plain. (Levine, p. 6 n. 10). (This pattern was repeated later: whenever the ruling power came out of the West, the coast developed and the central mountain region went into decline. After this happened with the Romans, it happened again with the Crusaders, and yet again, in the 20th century, with Jewish immigration from Europe. Today most Israeli Jews live on the coast between Tel Aviv and Haifa.)

Rome, then, had firmly established itself. The immediate symbol of this transformation was the city of Caesarea Maritima and its harbor, Sebastos. For the first time, Roman architecture appeared: a theater, a hippodrome, a nymphaeum, and a temple to both Rome and the emperor-god Augustus. How strange it must have felt to a Jewish or Samaritan hillbilly wandering into the city - a temple to a man? And inside were the statues of these gods, based on famous sculptures of Hera and Zeus. 

Little remains upon Herod's platform today. At present (March 2019) it is inaccessible because of reconstruction. When it is reopened, the chief reason to stand here will be to discern the ruins of the harbor beneath the sea and reconstruct it in imagination. Upon the platform itself are the foundations of the temple to Rome and Augustus, along with those of the octagonal Byzantine Church that replaced it. Just south of these stand the walls of a Crusader chapel. One can find shade here and remember some of the immense Christian history at Caesarea (our next topic).