The Fountain of the Turtles duplicated in San Francisco.

The 16th century Fontana delle Tartarughe (the Fountain of Turtles) by Giacomo Della Porta and Taddeo Landini was commissioned by the Mattei family whose Palazzo is just around the corner on Via Caetani.
One of the few fountains in Rome built not for a Pope, but for a private patron!
A popular legend claims that the Duke Muzio Mattei ruined by gambling, ordered the fountain to be built overnight to win the trust of the wealthy father of a woman he wished to marry. The next morning he opened the window of his palazzo and showed his future father in law the fountain. The father was impressed and allowed the marriage to go ahead and the Duke to remember the event, had the window overlooking the fountain closed up. A window closed by brick still overlooks the fountain.

The four turtles were added during a XVII century restoration ordered by Pope Alexander VII. They are usually attributed either to Gian Lorenzo Bernini or Andrea Sacchi. The date of the restoration is recorded on four scrolls of marble around the fountain. The theme of the fountain could be Festina lente, the neoplatonic saying “make haste slowly”.

The turtles are very realistic: they may have used casts of a real turtle. Initially, dolphins the same as the dolphins at the bottom, should have decorated the rim, but these were, in the end, transferred to the Fontana della Terrina (now in piazza della Chiesa Nuova, but without the dolphins).
In 1853-54, during a brief period of puritanism in Rome, leaves were placed over the sexual organs of the boys. In 1979 one of the turtles was stolen from the fountain. After the theft the original turtles were replaced by copies.

A replica of the fountain made in Rome in the early 1900s, was bought by William H. and Ethel Crocker for their estate at Hillsborough, California. It was given to the city of San Francisco by their four children and installed in Huntington Park, Nob Hill, in 1954.

The one in Rome.

The replica in San Francisco.