"The Church of St. Nicholas in Bari is named in the Law of Madrid of 1202 as one of the oldest parishes in the city. Today it is the oldest church in Madrid, after the demolition of the Church of Santa Maria de la Almudena. Archaeological remains suggest that the church and its bell-tower may have been part of a former mosque. It was likely constructed during the 12th century. The nave and chapels were renovated in the 17th century." -- Wikipedia