Quinta da Regaleira it's a Palace with huuuge gardens and
it is one of my favorite places in Lisbon. It’s not just that the Palace is beautiful and so interesting to visit (the library is amazing!) it’s also about the gardens... They’re full of beautiful corners, underground passages, and an amazing well. It’s unbeatable to walk around and imagining how people used to lived there.
It's a magical place. That's all i can say.