The Colleoni Chapel is the work of Giovanni Antonio Amadeo, commissioned and financed by Bartolomeo Colleoni, who had originally wished to be buried in Venice.

The richly decorated marble façade features sculptures, carved heads, medallions, and both round and square columns.
Inside are the tombs of Bartolomeo himself and his daughter Medea. The chapel, with its grand dome, was built in the 15th century to honor the famous mercenary and devout Christian Colleoni.

His symbol, which resembles three inverted hearts, appears throughout the chapel. Sometimes the shapes look like quotation marks, sometimes like teardrops — and sometimes, like what they were truly meant to represent: three pairs of swinging testicles.

This is a pun: the Italian slang word for testicles, “coglioni,” sounds very similar to Colleoni.
This symbol even inspired a legend that Bartolomeo had one more testicle than other men, something that was said to match his extraordinary bravery.

To this day, visitors to the chapel rub the sculpted “testicles” for luck, fertility, and masculinity — which is why they appear so particularly polished.