Via Nicolò Piccolomini in Rome is a hidden gem that offers an incredible optical illusion. At first glance, it appears to be an ordinary street with houses and apartment buildings on either side. But when observed from certain angles while driving or walking, the dome of St Peter's Basilica shrinks and becomes more distant at fast speed, creating an other-worldly feeling. The stunning view can be experienced day or night and all visitors will be left amazed by this little-known secret.