I don’t think they do implosions in crowded urban areas. Even though it looks like implosions are nice clean ways to take down buildings, they still send out debris for blocks. It can work if there is nothing else around (See the Kingdome, which was surronded by parking lots).
I just saw on the news yesterday, they brought down a 20-story building that was adjacent to a much taller building.. but i dont remember what city it was in.