This is commercial building with rooftop restaurant. Looks pretty cool and from this place you have great view on Prague Castle and riverside. You can take really nice pictures from this place.
adress:
Tančící dům
Rašínovo nábřeží 1981/80
120 00 Praha
gmaps: goo.gl/maps/oi2hv
closest station: Jiraskovo namesti (tram)