The museum, or site, is located below a bank building, the Millenium BCP. Thanks to some restoration work they started in the 90’s, they discovered this whole are of underground remains of more than 2,500 years of the city’s history, and even greater, they decided to save it for the city history’s sake. In a whole block, under the building, you can witness Lisbon Visigothic, Islamic, Roman, Medieval and Pombaline history at the Archaeological Centre.
I arrived in Lisbon in early 2000, and it took me almost three years to find out about this spot, thanks to a great friend of mine who got me a night visit. Before that I used to cross Rua Augusta and stop in front of the Bank windows to stare at the museum articles they have on display, but foolishly never imagined there was really a museum inside there.
Worse, I never imagined there were galleries under the building. It is actually a criptoportico, and it is a very nice visit. They even have an unidentified skeleton around there, that moves constantly where the caves flood. Besides the Bank site, the only other opportunity to see the criptoportico is once in a year, when the fireman close rua da conceição to open the only other access to it.
The Lisbon Baixa neighbourhood is full of surprises, and I consider this spot one of many good ones!