In Piazza di Pietra, there is an ancient structure rarely mentioned in guidebooks. There are 11 Corinthian columns, 15 meters high, a remnant of the temple of the 2nd century A.D. built in honor of Emperor Adrian (Tempio di Adriano), which Carlo Fontana in 1675 gracefully incorporated into the baroque customs building with a gesture. In 1878 the building was rebuilt for the Roman stock exchange and chamber of commerce. The ancient fragments had been cleaned of the seventeenth-century superstructure. We ended up in Piazza Di Pietra when we were viewing the Trevi Fountain and the Pantheon dbfahrplan.com. And came out to this piazza.