An imposing building with cylindrical towers stands out on the steep hill of Mertola, a southern Portuguese town on the banks of the Guadiana river, not far from the Spanish border.

Is it a church with a mihrab? Or a mosque with a cross?
The whitewashed building with horseshoe arches is known as the church of Nossa Senhora da Anunciacao. Those who come to visit its vaulted interior are told it’s the best preserved medieval mosque in Portugal.
“It’s a mixture of many things,” says Germano Vaz, who is from Mertola and lives nearby. “It was built on top of a Roman temple. It was a mosque and now it’s a church. We are very proud of this assemblage of religions and cultures.”
Inside the church that used to be a mosque, Christians still pray facing Mecca. The mihrab, a semi-circular niche in the wall, is directly behind the main altar.
A bell tower stands where, less than a thousand years ago, a minaret would call Muslims to prayer.
Read more at the source:
https://www.middleeasteye.net/discover/portugal-celebrates-islamic-heritage-al-andalus