The coats of arms of the popes who ruled the Eternal City for centuries can be seen on buildings and monuments throughout Rome.
A papal coat of arms is easily identifiable, as the shield will be surmounted by the triregnum (triple tiara or triple crown)* and a pair of crossed keys.
*In 2005, Pope Benedict XIV elected to have a mitre instead of a triregnum and this practise was adopted by his successor, Pope Francis.