The Mezquita-Iglesia de El Salvador is a church in Toledo, Spain completed in 1159.
Although the church is small, it is an exceptional building, because it was the site of 4 successive constructions, one on other and so on. It's a 12th-century church built on an 11th-century Taifa mosque, which was an expansion of a 9th-century Umayyad mosque and in turn on a Visigothic religious building. Also these civilizations reused 2nd-century Roman elements.
Have to say that is very-usually at the al-Andalus territory that Muslim liked to build on Visigothic buildings.
More information on Toledo's official website http://www.toledo-turismo.com/en/mosque-of-el-salvador_147
Address Plaza del Salvador, s/n 45002 Toledo, Spain
Coordinates 39°51'23.703" N -4°1'36.11" E