The official name is the Basilica di Santa Maria del Fiore (Basilica of Saint Mary the Flower). But those with a little travel savvy simply call this dominating structure the Duomo. Begun in 1296, this UNESCO World Heritage site -- the largest brick dome ever constructed -- sits in the center of Florence like a beacon for lost souls. The interior is covered in extraordinary frescoes, especially the 140-foot dome. Don’t miss the nearby Duomo Museum, where many of the original sculptures and masterpieces were moved to preserve them.