a Porta Latina
(Italian: "Saint John Before the Latin Gate") is a Basilica church in Rome
, near the Porta Latina (on the Via Latina) of the Aurelian Wall. It is currently the titular church of Cardinal Franciszek Macharski, former Archbishop of Kraków.
The tradition for the building of the Basilica of St. John at the Latin Gate places its construction during the pontificate of Pope Gelasius I (492-496). This is consistent with the oldest of the roof tiles, which have the imprint of a taxation stamp for the Ostrogoth King and ruler of Italy Theodoric the Great (reigned 493-526). One of these ancient roof tiles is now used in the Basilica as a lectern.
The main entrance to the Basilica is fronted by a small piazza with a 100-year-old cedar and an 8th-century well-head, nearly reproducing this aspect of the Basilica that would have been seen at the reconsecration of Pope Celestine III in the 12th Century.The portico (or porch) of the Basilica is supported by four re-used classical columns (each of a different marble) supporting five arches. The main door is framed with a simple mosaic of red and green porphyry.
The interior of the Basilica is divided into three naves, divided by two rows of columns on which rest semi-circular arches. The two columns closest to the sanctuary are of white marble with deep fluting. The other columns are of various types of marble and granite, capped with a diverse collection of Ionic capitals. The central nave terminates with a half-hexagon apse. Each of the three sides of the apse opens with a large window filled with honey-coloured onyx.
Occupying the ledge of the central window is a carved wooden crucifixion scene including Saint John the Evangelist and the Blessed Virgin Mary. In front of the altar is a mosaic pavement in Cosmatesque style. The geometric pattern of red and green porphyry is framed in white marble (as well are reused fragments of white marble with Latin lettering) is thought to have been created before the 12th century.