Portuguese Institute of Geography: LISBON
The Portuguese Institute of Geography is a fantastic find, which I visited in January 2020.
It's not really set up for tourists, and is located in a road just East of Rossio, one of the main squares in Lisbon.
Inside there is a museum which although not yet officially opened yet you might be able to access with a guide, who volunteered during our un-booked visit. There is also a library, map library and restaurant and bar. The map library is extensive and you can access the collection with some supervision. Unfortunately many of the oldest Portuguese maps were destroyed in the Lisbon earthquake and fire of 1755 which almost destroyed the city.
There are a number of exhibits here from the discoveries. A highlight for this Congo podcast is the Padrao, or stone cross, which was left by Diogo Cao at the mouth of the Congo in 1482 when his fleet of caravels met the people of the Kingdom of the Kongo.
The image below shows the main hall, which is surrounded by artifacts from old Portuguese colonies and still seats over one hundred people for lectures and debates.