There are loans. Usually they're secured by the assets, and you also cosign them personally. Your own credit worthiness comes to play, your own assets are in jeopardy.
As to what it is that you're buying - no, it is not necessary for the seller to sell you the building. You might buy the business, but not the actual space it occupies. In fact, the space may not even belong to the seller. You may find yourself taking over the lease, which is in fact a liability, not an asset.
You should agree with the seller on what exactly it is that you're buying. You should ask for a full inventory list that would include all the assets and the liabilities that would be transferred to you. Lease, as mentioned, but you might also "buy" loans, debts, lawsuits, and god knows what else that is attached to the business.