The square takes its name from the Parish Church of San Martino, built in the early seventh century on one of the islands called “Gemini” or “Gemelle” (twin), by peoples from the mainland fleeing the invasion of the Longobards, and rebuilt in subsequent centuries until it reached its current form in 1540 based on a design by Sansovino.
Stories from the past include the murder of Gaetano Marasso in the church in the early 1700s by count Domenico Althan, who was decapitated. It is said that he was dressed very elegantly on the day he was captured, and that as he was led to the gallows, he greeted his friends and spoke extensively before dying, ending with the sentence "Popolo addio" (“People, farewell”). 

Of the various public artworks in the square, notice a bas-relief in three parts: in the centre is San Martino giving his cape to a poor man, the lower section has an inscription flanked by volutes ending in lions’ paws on vases and connected by drapery to a cherub, and the upper section has an inscription topped by a lily cross.