Tree?

I have no clue what kind of tree this is, but they are all over town in Enschede. Sometimes there is just one tree like in this picture, and sometimes there are two or three trees that look like they've grown together. I'm assuming they're pruned to grow this way, but I have no idea what kind it is. I have some researching to do. I'm very anxious to see what they look like in bloom!

Tot ziens!