The national museum of 21st-century arts and architecture is in a Zaha Hadid-designed building as striking for its structure as it is for its content. 

Designed by three famous local architects, the baroque church also became known as the Church of Artists for its special Sunday mass with artist and musician accompaniment. You can still catch a special Sunday service at noon; otherwise, take a tour during the week. Follow it up with a visit to Santa Maria dei Miracoli across the street in Piazza del Popolo.