4Palazzo Doria Pamphilj

The Via del Corso is better known for chain-store shopping than for art, so most visitors and locals walk right past the gorgeous Palazzo Doria Pamphilj, which sits on the busy commercial thoroughfare. The severe square façade hides an enchanting porticoed courtyard, but the true spectacle is in the museum upstairs.

Though the main gallery only takes up four hallways, every visible surface is packed with oil paintings, frescoes and marble busts. The gilded hall of mirrors is the most breathtaking of all—and it is nearly always empty, given the museum’s hidden-in-plain-sight status. Look through the artwork that lines the wall to find paintings by Caravaggio and Tintoretto as well as Velazquez’s famed portrait of Pope Innocent X.