Hello, and thank you for your time answering my question. I am looking at buying a building near where I live, and the building itself is very old. I would guess late 1800's to early 1900's. I have noticed inside the building that the plaster walls have cracked in a few areas of the home, and the center of the building in all apartments are sagging. I am worried that there is some kind of problem with support or the infrastracture of the building itself. Is it a crack in the foundation I cannot see? Is it just gravity on the support beams? Is it fixable without spending more than the building is worth? Last but certainly not least, is it safe for tenants to live in? Thank you again for your time.