Receding floodwaters damaged two famed synagogues Friday, including the oldest Jewish temple in Central Europe, as experts began assessing the worst flood destruction in nearly 200 years.

Prague officials refused to let people return to some parts of the historic Old Town because of the danger buildings and palaces -- some built on sand -- could cave in and collapse under their own weight as waters recede.

Engineers across the Czech Republic, meanwhile, fought to save hundreds of other historical treasures, including the once-perfectly preserved medieval town of Cesky Krumlov in southern Bohemia, a UNESCO heritage site.

The flooded Otava River also tore a decorative statue, railings and stones from the country's oldest stone bridge, a 13th-Century span in Pisek, about 60 miles south of Prague.

Water also flooded the archives of the ministries of transport and agriculture, the Military Historical Archive, the Academy of Science, the Czech Philharmonic Orchestra and the Czech Statistical Office.

"The damage can be calculated in kilometers, which means tens of thousands of shelves with unique and irreplaceable documents," Miroslav Kun of the National Central Archive told the Czech news agency CTK.

While the raging Vltava River did not spill over barriers into the Old Town, groundwater and sewer levels surged to extraordinary heights, filling basements and soaking foundations.

The Old-New Synagogue, a 13th-Century landmark on the edge of Prague's Old Town, was swamped by nearly 3 feet of water that seeped into the main part of the temple.

The nearby Pinkas Synagogue, known for its etchings of the names of all 77,297 area Holocaust victims on its walls, was also flooded by 6 feet of water.

"The synagogue is seriously damaged," said Leo Pavlat, the director of the Jewish Museum in Prague. "I expect that the writing on the wall below the water line is completely destroyed."

He estimated that the synagogues and other Jewish Museum structures might have to be shut down for months -- if not years. Such a closure could prove devastating to Prague's small Jewish community itself, which relies on income from entrance fees.

The fees also support 800 elderly Holocaust survivors and a Jewish school.

Engineer Michal Borges, who supervises the Old-New Synagogue and other structures for the community, said the biggest problem was the stability of the structures themselves. He said he was not yet sure of the extent of the damage.

"We can't see anything yet," he said. "It's just darkness and dark water."

Vladimir Vihan, a deputy mayor in charge of cultural monuments and palaces, said much of the Old Town is built on sand -- and as the waters recede, the sand also will be swept away, leaving pockets underground and potentially making much of the historic district unstable.

Some streets in the Old Town already have caved in, he said.

"We fear that in the coming days and weeks, houses, palaces and more streets will cave in," Vihan said.