There are plenty of dwarf fruit trees and bushes. There is no excuse for not enjoying the taste of fresh fruits and berries at least once in your life. Strawberries can be grown in the smallest of pots, in a sunny nook on the deck. But an orchard in a small space takes backward thinking.
Espalier is the art of growing fruit and other trees flat against a wall. It first became popular in Medieval Europe. Evidently they too had limited growing space in their walled gardens. Espalier trees are pruned and trained to grow two dimensionally. Besides taking up less space, training the trees against a sunny wall creates a warm microclimate. Fruit trees that wouldn't ordinarily bear in cooler zones, can be fooled in thinking they are a zone warmer. Additionally, the open framework of an espalier lets in more sun, encouraging more blossoms and faster ripening. A final benefit is how beautiful the trees look asking in the sun against your home and how impressed all your gardening friends will be.
Apples and pears are the most common fruit trees used with this technique. However stone fruits, like peaches, cherries and plums, can also be trained, although the pruning schedule will be different. The trees in this photo are planted in a border not much more than a foot wide.