This in the Slovak Radio building in Bratislava (Slovakia). As you can see it’s a pyramid upside-down. The architects were Stefan Svetko, Stefan Durkovic and Barnabas Kissling. The build started in 1967 and was completed in 1983, because it took such a long time some call it “the building of the century”.
You can find this piece of architecture on the list of the 30 ugliest building of the world but I think it looks amazing.