Slang: hole in the wall

Definition: A small, simple place, particularly a shop or restaurant.
Example: 1) Let's go to the Italian restaurant on Smith Street. It's just a hole in the wall, but the food is excellent.
Etymology: This phrase has been used since the early 1800s. A 'hole' is an empty space, and a 'wall' is part of a building. So a 'hole in the wall' is a simple, undecorated space in a building.