Quinta da Regaleira is a Romantic palace and chapel, surrounded by a green area full of lakes, wells, fountains, tunnels and sculptures, situated right next to Sintra's historic center. The property had many owners throughout the centuries.
Perhaps the most widely-known element within Quinta da Regaleira is the so-called Poço da Iniciação ("Initiation well"). This is a 27-meters spiral staircase, which is remarkable from an architectural point of view.
Please make sure you wear comfortable footwear to walk all the way up and down steep streets and tracks. Also, speaking of Sintra, one should always be prepared for wind and rain up there.