The 'Sallustiano' obelisk originally stood in the Horti Sallustiani, the gardens of the historian Gaius Sallustius Crispus (86-35 BCE). The gardens, which covered a large area between Porta Pinciana and Porta Salaria, later became imperial property.
At some point during the mists of time, the obelisk fell or was felled, but it was never completely lost. In 1735 Pope Clement XII (r. 1730-1740) had it moved to Piazza di San Giovanni, where it lay for decades. It was finally erected in 1789, by order of Pope Pius VI (r. 1775-99), in front of the church of Santissima Trinità dei Monti.
There are three inscriptions on the base. The two short inscriptions read: III EIDVS / APRIL / ANNO M DCC / LXXXVIIII (The third day before the Ides of April in the year 1789) and SACRI / PRINCIPATVS / EIVS / ANNO XV (The fifteenth year of his pontificate).
The longer inscription, on the west face, reads: PIVS · VI · PONT · MAX · / OBELISCVM · SALLVSTIANVM / QVEM · PROLAPSIONE · DIFFRACTVM / SVPERIOR · AETAS / IACENTEM · RELIQVERAT / COLLI · HORTVLORVM / IN · SVBSIDENTIVM · VIARVM / PROSPECTV· IMPOSITVM / TROPAEO / CRVCIS · PRAEFIXO / TRINITATI · AVGVSTAE / DEDICAVIT (Pius VI, Pontifex Maximus, dedicated to the august Trinity the obelisk of Sallust, which, broken in its fall, a former age had abandoned prostrate, set atop the hill of the gardens in view of the streets below, and crowned with the victory trophy of the Cross).