Milestii Mici is an underground wine storage facility in Chisinau, the capital of Moldova. Here, 40-85 meters underground, is the world’s largest wine cellar, home to the aptly named “Golden Collection” of over 2 million bottles of wine.

The caves keeps the wine at a constant temperature between 12-14 degrees Celsius (53-57 degrees Fahrenheit) with constant humidity year-round. This steady environment maintains the wine to perfection and produces some of the most expensive aged red wine in the world.

Created in the typical Moldovan winemaking process in a factory above ground, the collection stretches over 150 miles. It’s so large that visitors and employees navigate the underground network with bikes and cars, with each street named for the wine it holds. Although the collection is massive at present, Milestii Mici still has room to expand: Only half of the total length of the tunnels is presently being used.

Tours of the wine tunnels are available every day and wine tastings and appetizers in one of the traditionally decorated Moldovan tasting rooms are available in many of the various tour packages.