High Quality Content by WIKIPEDIA articles! The Charles V Wall is a 16th-century defensive curtain wall that forms part of the fortifications of the British Overseas Territory of Gibraltar. It was built in 1540 and strengthened in 1552 by King Charles I of Spain, the Emperor Charles V. The wall remains largely intact and extends from South Bastion, which was once at the water`s edge in the harbour, to the top ridge of the Rock of Gibraltar.