The original Southport Gate was formerly known as the Africa Gate, and was the earliest of the trio of gates built in the Charles V Wall. It was constructed by Italian engineer Giovanni Battista Calvi in 1552. The Southport Ditch was a large trench which extended along the south side of Charles V Wall from the southwestern end of the South Bastion to the Flat Bastion and Prince Edward’s Gate.
The central gate was constructed in 1883 and was known as the New Southport Gate. It was opened in the Charles V Wall to improve the flow of traffic and was constructed during the reign of Queen Victoria. It is ornamented with the coat of arms of Gibraltar, the Governor and the Royal Arms of Queen Victoria.
The third gateway, known as Referendum Arch was built in 1967 and is the large of the three gateways.
During the 19th century, the Southport Ditch between Ragged Staff and Southport Gate was used as the Ordnance Depot. Images survive showing heavy guns and shells stored in piles at this area.
The gun presently mounted inside the gateway is one of the four 10-inch rifled muzzle loading guns formerly mounted in nearby South Bastion.