A massive storm that battered the eastern Mediterranean destroyed the breakers protecting the Roman-era port of Caesarea, threatening to wash away the historic site, Israeli officials said.
“Now the port is exposed to the full force of the waves,” said Zeev Margalit, the head of development and preservation at the Israel Nature and Parks Authority.
“It is a matter of time until it all collapses.”
Mr Margalit said the agency had warned the government several times in recent months of the danger to the port, which was built by Herod and served as the seat of government for Pontius Pilate.
At the scene, hundreds of large stones lay scattered across the jetty which appeared to have sustained heavy damage from the storm.
High winds of up to 100kph whipped up enormous waves, some as high as 12 metres, which continuously battered the ancient port.
The ruins of the port city, one of the largest in the region in Roman times, is a major tourist attraction in Israel and the Roman amphitheatre continues to host concerts.
It also contains the remains of dozens of buildings from the subsequent Byzantine and Crusader periods, including the moat and fortified walls that surround the site.
In recent times Caesarea has become an upscale residential town, home to some of Israel’s wealthiest and most influential citizens.
Prime minister Benjamin Netanyahu has a weekend home in the town, 50km north of Tel Aviv.
Mr Margalit said it would cost about 60 million shekels ($16 million) and take three years to construct a new, modern wave breaker to protect the site.
However, he said the authority had also proposed a $1.6 million emergency plan that would involve construction of a temporary wave break.
“If Israel does not react immediately then a major international heritage site will be lost,” he warned.