This temple, built in 145 by emperor Antoninus Pius, was dedicated to the worship of the emperor's deceased adoptive father, emperor Hadrian.
Such a practice was nothing unusual for Romans. Starting from the first emperor, Augustus, emperors were usually proclaimed divine after their deaths and many of the more popular ones, like Hadrian, were given a temple or several to be worshipped in.
Originally, it was a majestic structure with a 4-meter-high podium and thirty-eight 15-meter-tall columns. In the 17th century, pope Innocent XII decided to incorporate the temple into a newly-built customs office though.
Thus, all that remains of Hadrian's temple today is a row of 15 columns along with one of the walls, made from a volcanic tuff. You can also view some of the decorative reliefs which used to be a part of the temple in the Capitoline Museum.
Today, the Temple of Hadrian houses the Borsa Valoridi Roma, Rome’s stock exchange.
Wikipedia https://en.wikipedia.org/wiki/Temple_of_Hadrian
Address Piazza di Pietra, 00186 Roma, Italy
Coordinates 41°53'59.103" N 12°28'45.946" E