The Temple of Hadrian is a temple to the deified Hadrian on the Campus Martius, built by his adoptive son and successor Antoninus Pius in 145 and now incorporated into a later building in the Piazza di Pietra. It was once erroneously known as the Temple of Neptune. One wall of the cella survives, together with eleven of the 15-metre-high Corinthian columns from the external colonnade, on a 4 m highpeperino base. The fixing holes for its original marble covering can still be seen. This facade, along with the architrave, was incorporated into a 17th-century papal palace by Carlo Fontana, now occupied by the Borsa bank. The building wasoctastyle and had 15 columns on each long side.