Narodní památník hrdinů Heydrichiady

This is an aspect of WWII history about which I knew very little before visiting this museum. The displays were quite interesting with English descriptions available. The memorial to the heroic challengers of Nazi oppression who died fighting during this series of events was appropriate and well done. Being at the place at which these brave men died was seminal to the experience. It was not hard to be caught up in the drama of the events while reading the account of their last moments when the Nazis closed in on them. It was also particularly poignant to read about the rounding up and execution of their collaborators.
This is typically not listed as one of the top tourist sites in Prague. I definitely recommend adding this to your itinerary if you have any interest at all in WWII history or local culture. The nominal fee (75 CZK, or about $ 3 USD at the time I visited) is well worth it.