The obelisk was unearthed (broken into several pieces) in 1519, near the ruins of the mausoleum. However, it wasn’t until the reign of Pope Sixtus V (r. 1585-90) that it was re-erected. In 1587 the pope had it set up in the piazza in front of the entrance to his property, Villa Peretti Montalto. The villa was destroyed in the 19th century to make way for the building of Stazione Termini, Rome's main railway station.
The base sports four inscriptions, which were added at the behest of Pope Sixtus V.
South-west face: SIXTVS V PONT MAX / OBELISCVM / AEYGPTO ADVECTVM / AVGVSTO / IN EIVS MAVSOLEO / DICATVM / EVERSUM DEINDE ET / IN PLVRES CONFRACTVM PARTES / IN VIA AD SANCTVM / ROCHVM IACENTEM / IN PRISTINAM FACIEM / RESTITVTVM / SALVTIFERAE CRVCI / FELICIVS / HIC ERIGI IVSSIT AN D / MDLXXXVII PONT III. (Pope Sixtus V bade the obelisk lying in the street by San Rocco, which had been transported from Egypt and dedicated to Augustus at his mausoleum, then broken up into several pieces, to be restored to its original appearance and erected here in more auspicious wise to the Cross which brings salvation, in the year of the Lord 1587, the third of his pontificate.)
South-east face: CHRISTVS / PER INVICTAM / CRVCEM / POPVLO PACEM / PRAEBEAT / QVI / AVGVSTI PACE / IN PRAESEPE NASCI / VOLVIT. (May Christ, who during the peace of Augustus consented to be born in a manger, grant peace to his people through the invincible Cross.)
North-east face: CHRISTI DEI / IN AETERNVM VIVENTIS / CVNABVLA /LAETISSIME COLO /QVI MORTVI / SEPVLCRO AVGVSTI / TRISTIS / SERVIEBAM. (I who in sadness formerly served the tomb of the dead Augustus with greatest joy revere the cradle of Christ, the everliving God).
North-west face: CHRISTVM DOMINVM / QVEM AVGVSTVS / DE VIRGINE / NASCITVRVM / VIVENS ADORAVIT / SEQ DEINCEPS / DOMINVM / DICI VETVIT / ADORO. (I worship Christ the Lord, whom Augustus in his lifetime worshipped on the eve of his birth from a Virgin and subsequently forbade himself to be called Lord.)