The Enver Hoxha Museum – also known as the Pyramid – is easily one of the most remarkable buildings in Tirana. It was built in 1988 to serve as a museum about Albania’s communist-era dictator, but following the end of communism, it has served a wide variety of purposes. It’s been home to NATO, a TV channel, and I believe at the moment, an international cultural center. There are perennial discussions of tearing it down and building something in its (very prominent downtown) spot, but so far they have come to naught.
It is also servers as an enormous slide to the children of Tirana. I wanted to give it a go myself when I was there, but chickened out when I got to the base of the building and realized how steep the sides are.