The phrase "old building" refers to a structure that has been around for a long time. It usually implies that the building is not new and may have historical or traditional significance. Full definition
Children who live in old buildings in which lead still exists in the plumbing or in lead paint that has been painted over may be at risk. (childdevelopmentinfo.com)
There have to be a lot of older buildings with interesting stuff underneath. (sbnation.com)
I saw schools with modern equipment and schools in old buildings with little equipment. (educationworld.com)