The oldest restaurant in the world is in...
... Spain, specifically in Madrid. And its name is Casa Botín. This merit is confirmed by the Guinness Book of Records.
Its location is behind the Plaza Mayor, in the typical Madrid street of Cuchilleros belonging to Madrid de los Austria.
Its origin dates back to 1725, when the French chef Jean Botín created the restaurant, and the current restaurant's wood-fired oven is from that year.
The restaurant has three floors, with dining rooms on the lower floor in typical Spanish caves like many restaurants, its origin being the old cellars previously used as warehouses. It also has a dining room on the entrance floor with the decoration of the 19th century reform with polychrome wood friezes in gold leaf, as well as the window and counter of the time. Eating there both for the restaurant and for its cuisine takes you back 200 years, and it is a balm for the heart.
It is the typical Castilian cuisine restaurant with main products such as roast lamb and suckling pig made in its old wood oven.
An anecdote that certifies the Guinness Book of Records: the famous painter Francisco de Goya worked as a teenager in the restaurant in 1765.
This is its website, where you can check its schedules, menu, prices and information to reserve:
Restaurant Casa Botín