Trompe L’Oeil

http://commons.wikimedia.org/wiki/Image:Sant%27Ignazio_-_painted_dome_-_antmoose.jpg
Image: Wikimedia Commons

Designers wanted to put a dome on Rome’s Sant’Ignazio church, but neighbors complained of the shadow. So, instead, artist Andrea Pozzo painted this design on the flat ceiling.

When it’s viewed from the side (below), the church gets its dome after all.

http://commons.wikimedia.org/wiki/Image:Ignazio.jpg
Image: Wikimedia Commons