Everything that goes up must come back down. This is true for everything affected by gravity, including buildings. Demolishing buildings is actually a business, because of how complicated it can be. Sometimes just a bunch of heavy equipment and a few machines will suffice, but with larger buildings like offices and skyscrapers, keeping,the rubble inside the lot as it collapses is a big deal.
The way this is done is usually by using controlled explosions going off in sync. The way these explosives are placed is typically on the very center, on support beams and anything structurally integral. This way, all of the rubble falls inward, not intruding on roads and other buildings. Obviously, if a building collapses onto another one it can't end well, so the scientific destruction of buildings is a significant practice. Having been to watch a building being demolished, I can say that it is very loud, and the ground shakes a lot, so much so that it can be mistaken for an earthquake. After it collapses, the dust cloud it sends up is massive, and rushes out sideways.