Venice’s Jewish ghetto is considered the first in Europe and one of the first in the world, and a new effort is under way to preserve its 16th-century synagogues for the Jews who have remained and tourists who pass through.

For nearly two years, restorers have been peeling away paint and discovering the original foundations of three of the ghetto’s synagogues, which are considered the only Renaissance synagogues still in use, art historian David Landau said.

Mr Landau is spearheading a fundraising effort to restore the synagogues and nearby buildings both for Venice’s small Jewish community, which numbers around 450 people, and for tourists who can visit them on a guided tour through the Jewish Museum of Venice.

Mr Landau, a Renaissance specialist who bought a home in Venice 12 years ago, said: “I was really deeply offended by the state of the synagogues. I felt that the synagogues were in very bad condition. They had been altered beyond recognition over the centuries, and needed to be kind of cared for and loved.”

He has secured about 5 million euros (£4.3 million) to date and expects workers can complete the restoration process by the end of 2023 if the rest of the funding comes through – although the original outstanding 4 million euros (£3.4 million) has now ballooned to 6 million (£5.1 million) because of soaring building costs.

Venice’s ghetto dates from 1516, when the republic forced the growing numbers of Jews into the district where the old foundries, or “geti” as they were known, had been located.

The area, which was locked down at night, became what is considered Europe’s first ghetto and remains the hub of Venice’s Jewish community in the Cannaregio area.

The first synagogue dates from 1528 and was built by German Ashkenazi Jews. Others followed and served different groups, including one for Spanish Sephardic Jews and one for Italian Jews.

None is visible from the street, as strict rules imposed by Venice’s rulers did not allow Jews to practice their faith openly. All the synagogues are hidden away on the top floors of seemingly normal buildings that on the lower levels held cramped living spaces for Jewish families.

The synagogues have remained operational continuously, except for the years of the Second World War during the German occupation.

Dario Calimani, head of Venice’s Jewish community, said the restoration project is necessary both to maintain the religious and cultural life of Venice’s Jews today and to preserve the community’s history.

“They are a testimony to the life that it was, to the history of our community, small community,” he said.