Backdoor 43 is reportedly the world's smallest cocktail bar — a 4-square-metre Navigli room that holds four people at a time, with a fixed cocktail menu and strict reservation-only format.
The cocktail programme rotates monthly with three or four builds. Time slots are 30 minutes per group of two-to-four. The room is reservation-only and books months ahead. Architectural conceit and one of Milan's most-photographed cocktail rooms.