How do I replace these baseboards?

[Byron W.]

Hey everyone, just purchased a building. I'm not 100% sure what the walls are made of.. Seems like they could be plaster but I'm not sure. Anyways, I'd like to update some things in this place and the ugly baseboards are one of the first things I'd like to get rid of. However, they're unlike any baseboard's I'm used to seeing. They almost sit flush with the wall. The wall's have a lip at the bottom and under that lip are the baseboards. Almost like the wall ends where the baseboard begins. Can anyone give any advice on how to remove these? Also, do I need a special kind of baseboard for replacing them? Or are any baseboards gonna do the trick? Thanks!