Behind the Piazza Colonna is the _Piazza Monte Citorio_, containing an _Obelisk_ which was discovered in broken fragments near the Church of S. Lorenzo in Lucina. It was repaired with pieces of the column of Antoninus Pius, the pedestal of which may still be seen in the Vatican garden. Its hieroglyphics are very perfect and valuable, and show that it was erected more than 600 years before Christ, in honour of Psammeticus I. It was brought from Heliopolis by Augustus, and erected by him in the Campus Martius, where it received the name of Obeliscus Solaris, from being made to act as a sun-dial. "Ei, qui est in campo, divus Augustus addidit mirabilem usum ad deprehendendas solis umbras, dierumque ac noctium ita magnitudines, strato lapide ad magnitudinem obelisci, cui par fieret umbra, brumæ confectæ die, sexta hora; paulatimque per regulas (quæ sunt ex die exclusæ) singulis diebus decresceret ac rursus augesceret: digna cognitu res et ingenio fœcundo. Manilius mathematicus apici auratam pilam addidit, cujus umbra vertice colligeretur in se ipsa alias enormiter jaculante apice ratione (ut ferunt) a capite hominis intellecta. Hæc observatio triginta jam ferè annos non congruit, sive solis ipsius dissono cursu, et cœli aliqua ratione mutato, sive universa tellure a centra suo aliquid emota ut deprehendi et in aliis locis accipio: sive urbis tremoribus ibi tantum gnomone intorto, sive inundationibus Tiberis sedimento molis facto: quanquam ad altitudinem impositi oneris in terram quoque dicantur acta fundamenta."--_Plin. Nat. Hist._ lib. xxxiv. 14. _The Palace of the Monte Citorio_ (designed by Bernini) contains public offices connected with police, passports, &c. On the opposite side of the piazza are the Railway and Telegraph Offices. Proceeding up the Corso, the Via di Pietra (right) leads into the small Piazza di Pietra, one side of which is occupied by the eleven remaining columns of the _Temple of Neptune_, built up by Innocent XII. into the walls of the modern Custom-house. It is worth while to enter the courtyard in order to look back and observe the immense masses of stone above the entrance, part of the ancient temple,--which are here uncovered. Close to this, behind the Palazzo Cini, in the Piazza Orfanelli, is the _Teatro Capranica_, occupying part of a palace of _c._ 1350, with gothic windows. The opposite church, _Sta. Maria in Aquiro_, recalls by its name the column of the Equiria, celebrated in ancient annals as the place where certain games and horse-races, instituted by Romulus, were celebrated. Ovid describes them in his Fasti. The church was founded _c._ 400, but was re-built under Francesco da Volterra in 1590.