The Colle Oppio was home to some of the most luxurious residences in Rome before it was expropriated by Nero. At the edge of the hill, the church of San Martino ai Monti was built above a Roman building which can still be visited from the crypt.

The ancient church has changed greatly over the years, with the last reconstruction in the 16th century. The 3rd century vestibule predates the great hall of the church proper which was constructed with a cross- vaulted ceiling resting on pillars.
It seems that it was part of the property belonging to the Presbyter whose name was Equitius; it therefore was known as Titulus of Equitius. The Latin word "titulus" was the nameplate affixed to the door of a building showing the owner's name but later was used for parish churches.
"Titoli" churches were not only for celebrating the liturgy but were also where both the Faithful and the Catechumens received religious instruction, and where, even before Christianity became legal in Rome, the early Christian community provided social assistance to the poor and needy.