Iron Gate, Roman gate of Diocletian's Palace in Split, Croatia

The Iron Gate is the western entrance to Emperor Diocletian's ancient palace and connects modern city streets to the interior of the historical complex. The passage features a vaulted corridor with arcaded sections and is crowned by the Church of Zvonik, which separates the gate from the outer passageway.

The gate was built in the 4th century during Emperor Diocletian's reign as a military entrance and later served as a courthouse during medieval times. As the palace declined and the city grew around it, it evolved into a central passage connecting old and new quarters.

Above the gate stands the Church of Our Lady of the Belfry, first dedicated to St Theodore in the 6th century and rebuilt in the 11th, when the pre-Romanesque bell tower was added. The tower is the oldest preserved on the Adriatic coast, and the church keeps an image of Our Lady of the Belfry.

The gate sits mid-way along the west wall of Diocletian's Palace, on the east-west line of the ancient via decumanus that ends at the Silver Gate. The passage is 1.20 m wide, with a threshold about 1 m lower than today's floor, and stairs beside it lead up to the patrol corridor. The corridor is roughly 5.20 m high and 2.22 m thick in the wall.

The city clock on the gate has 24 digits instead of the usual 12. The gate also preserves the only spot in the palace where the top of the main perimeter wall is visible, at a relative height of 15.75 m, with the original stone slab cover still in place.