The Matriz Church of Mertola is situated at Rua Elias Garcia. It is also known as Igreja Matriz de Nossa Senhora da Anunciacao. This building was originally a mosque built between 12th and 13th centuries. After the Christian conquest of the town, in 1238, the mosque was turned into a church. The decorations above the walls of this church are similar to those ones in the Great Mosque of Cordoba. The bell tower of this church was once a minaret of the mosque. Later, church bells were added at the top of the old minaret.