Near this, turning right, is the _Piazza di Campitelli_, which contains the _Church of S. Maria in Campitelli_, built by Rinaldi for Alexander VII. in 1659, upon the site of an oratory erected by Sta. Galla in the time of John I. (523-6), in honour of an image of the Virgin, which one day miraculously appeared imploring her charity, in company with the twelve poor women to whom she was daily in the habit of giving alms. The oratory of Sta. Galla was called Sta. Maria in Portico, from the neighbouring portico of Octavia, a name which is sometimes applied to the present church. The miraculous mendicant image is now enshrined in gold and lapis-lazuli over the high altar. Other relics supposed to be preserved here are the bodies of Sta. Cyrica, Sta. Victoria, and Sta. Vincenza, and half that of Sta. Barbara! The second chapel on the right has a picture of the Descent of the Holy Ghost by _Luca Giordano_; in the first chapel on the left is the tomb of Prince Altieri, inscribed "Umbra," and that of his wife, Donna Laura di Carpegna, inscribed "Nihil;" they rest on lions of rosso-antico. In the right transept is the tomb, by _Pettrich_, of Cardinal Pacca, who lived in the Palazzo Pacca, on the opposite side of the square, and was the faithful friend of Pius VII. in his exile. The bas-relief on the tomb, of St. Peter delivered by the angel, is in allusion to the deliverance from the French captivity. The name Campitelli is probably derived from Campusteli, because in this neighbourhood (see Ch. XIV.) was the Columna Bellica, from which when war was declared a dart was thrown into a plot of ground, representing the hostile territory,--perhaps the very site of this church. In the street behind this, leading into the Via di Ara Cœli, are the remains of the ancient _Palazzo Margana_, with a very richly-sculptured gateway of _c._ 1350. Opening from hence upon the left is the _Via Tor de' Specchi_, whose name commemorates the legend of Virgil as a necromancer, and of his magic tower lined with mirrors, in which all the secrets of the city were reflected and brought to light.