The Ngome Kongwe, or Old Fort, is located in Stone Town on the seafront next to the House of Wonders. It was built in 1698-1701 by the Busaidi Omani Arabs on the site of an earlier Portuguese church, remnants of which can be seen built into the walls in the main courtyard. The fort is a large building with high brown crenelated stone walls. It was originally built as a defense against the Portuguese and a rival Omani group, then used as a prison in the 19th century and a railway depot in the early 20th century.