Fontana delle Tartarughe - Turtle's Fountain

A jewel inside the Jewish Ghetto. A fountain by Giacono della Porta commissioned by the Mattei family, then adorned by bronze sculptures (turtles, dolphins and Pans).

The piazza is named after the Mattei family, one of the most powerful families in Rome during the Renaissance.this fountain was built indeed, by the Mattei family.
There is a nice story about the construction of this fountain.

Four ephebes (adolescent boys) cavort around the base of one of Rome's loveliest fountains, gently hoisting tortoises up to the waters above them.

According to legend, Giacomo della Porta and Taddeo Landini built the fountain for the Duke of Mattei at some point in the 1580s. The duke, so

the story goes, had lost all his money and hence his fiancée, and wanted to prove to her father that he could still achieve great things. He had the fountain built overnight in the square outside his family palazzo (you can wander freely into the classical, carving-clad courtyard of the palazzo, now home to an American studies centre); the next morning he triumphantly displayed his

accomplishment from a palace window.

The wedding was on again, but he had the window walled up, and so it remains. The turtles were

probably an afterthought, added by Bernini during a restoration.

The ones there today are copies: three of the originals are now in the Capitoline museums; the fourth was stolen and presumably graces some private fountain.