The Church of St. Martin is inserted into the corridor above the Porta Aurea of Diocletian's Palace in Split and is preserved until today. Above the outer entrance of the North Gate, which later became known as the Golden Gate, is a well-preserved adapted and narrow church of St. Martin.
The space inside the Church was rearranged several times, and the oldest probably belongs to the early Christian era. The pre-Romanesque phase, probably as early as the 9th century, includes a barrel vault, an altar in the apse with a carved cross of early Christian markings and small transepts (perforated stone slabs) placed in the middle of large walled antique openings on the south wall. The later pre-Romanesque phase from the 11th century belongs to the altar partition, the only one which is entirely preserved in Dalmatia. Remains of the bell-tower have remained on its Western side.
From the contents of the inscription, which is carved along the upper part of the fence, it is learned that the Church contains objects of worship (patrocinia) in honor of St. Martin, the Mother of God and Pope St. Gregory, which means that the Church is under their protection.
The Church has another inscription on the lintel, written in a rustic way, mentioning a priest Dominic, who is responsible for the construction work in the Church (for the construction of partition walls and doors).