At number 43 on Ripa di Porta Ticinese, a long, canal-side street filled with luxury restaurants, a minuscule wooden bar quietly stands out. BackDoor 43, as it is known, claims to be the world's smallest bar. Guests can book the space for one hour at a time, during which they'll find themselves spirited away from the hustle and bustle of city life in their own private club.  The bar is just 43 square feet (4 square meters) in size, including a bathroom.

There are just three stools for patrons to sit and sip upon. A key and a secret password are also required for entry. Most customers purchase their drinks through the tiny slot window, through which they can see the bartender's hands and not much else. Secrecy is key here: If takeaway drinkers do sneak a peek through the slot, they'll find the bartender's face obscured by a mask. BackDoor 43 announced its grand opening not with advertisements or promotions but with secret riddles and books hidden throughout Milan.

The bar uses every square inch of its closet-like space. From floor to ceiling, wooden apothecary shelves house alcohol, various herbs, flowers, and tinctures. Mugs dangle from hooks lining the walls. Betwixt the bottles are esoteric items that bring to mind a cabinet of curiosity, like diagrams of hot air balloons and antique magnifying glasses. The ceiling is papered with an old map, and the entire bar (all 13 square feet of it) feels like a secret speakeasy.   The bartender mixes on a tiny countertop complete with a camp stove. The night's menu is tailored for the guests.

Their ingredients are top shelf, with over 60 rare whiskeys alone, and drinks are served with classy, old-fashioned flair. The Bahamas is served in a retro tiki glass, while the Guatemalan Diamond comes in a gem-shaped glass served atop a pile of smoking roasted coffee beans. Whether leaving BackDoor 43 after two hours of private speakeasy relaxation or just walking away from the window with a paper cup of liquor in hand, you're sure to be left with a lingering sense of wonder in the small things.