Torre Rognosa, also known as the Clock Tower, is one of the tallest and best-preserved medieval towers in San Gimignano.
The tower was built around 1200 and belonged to the Gregorio and Oti families. The tower is 51 m high, making it the second tallest in the city after the Great Tower (54 m).

The name "Rognosa" comes from the fact that for some time the tower housed prisoners with scabies (from the French rogne).

At the top of the tower there is an open terrace with a bell tower. At first, the bell was rung to notify citizens of danger, but later the bell began to strike the hours (hence the alternate name - Clock Tower).