We would like to buy an old school with gym and other facilities .where to find this

Make sure the zoning for the old school meets your intended use. Older school houses do come up on MLS, however, their is never a large inventory. what is the area you desire?

Get a local agent to search for you and as Daryl says make sure the zoning conforms to the use you want to make of it.

Schools are commercial. Have an Agent perform a commercial search for you. Then if you wish to live in the building have the zoning checked before making an offer.