It was a church from 360 B.C. to 1453, and became a mosque from 1453 until 1931. In 1453 Sultan Mehmed laid siege to Constantinople, "driven in part by a desire to convert the city to Islam."
Hagia Sophia has a huge dome, typycally Byzantine Christian architecture and was the largest cathedral in the world for nearly a thousand years. As a mosque it was the principal mosque of Istanbul for almost 500 years.
Today it is a tourist spot. This is a photo of the exterior of the Hagia Sophia.
A shot of the interior, the main hall. There was some restoration work going on but here you can see the symbols of both Christianity and Islam. A painting of Christ at the top of the image and an Islamic symbol to the right of the picture.
Here is a photograph of the elaborately carved and painted interiors. Paintings of Christ are visible.
Another image of the inside of the domes and a small image of Jesus Christ.
Related Images: The Blue Mosque at Istanbul
There are also a lot of pictures of the Sistine Chapel in Vatican City in Rome on this website.
Or more related images: Church Silhouettes or Christmas Tree Silhouette