A City Underground
In Budapest’s 10th district, beneath the streets of Kőbánya, lies a vast network of tunnels that once supplied limestone for Hungary’s most iconic buildings. Spanning up to 35 kilometers in length and descending 30 meters below ground, this labyrinth began as a medieval quarry and evolved into a multifaceted underground complex.
Today, it remains largely hidden from public view, though parts are accessible during guided tours and events. Its immense size and versatility have allowed it to serve many roles over centuries—from quarry to brewery cellar, from factory to mushroom farm.
Stone for a Nation
Quarrying in Kőbánya likely began during the 13th century, with documented activity appearing in a royal charter by Béla IV. The quarry produced Sarmatian limestone, used in constructing the Parliament, Chain Bridge, Matthias Church, and other landmarks.
During the 19th century, the quarry’s activity peaked, and limestone was transported along the aptly named Fehér út (“White Road”), dusted in pale stone powder. Mining officially ceased in 1890 due to tunnel instability, though it continued sporadically into the 20th century.
From Barrels to Bombers
Above the tunnels, vineyards thrived from the 17th century onward. Abandoned tunnels became wine cellars, and following the phylloxera plague, breweries replaced wineries. In 1844, Péter Schmiedt established a brewery that later became part of the Dreher empire.
The tunnel system’s stable temperatures made it ideal for beer fermentation. During World War II, parts of the tunnels were repurposed as aircraft engine assembly plants, likely operated by the Danubian Aircraft Factory. Workers manufactured engines for the Messerschmitt Me 210Ca-1 before operations relocated due to advancing Soviet forces. The tunnels also served as a civilian air-raid shelter during the siege of Budapest.
Modern Ruins and New Plans
Nationalized in 1948, the complex’s postwar use was limited. It hosted mushroom farming until EU regulations outlawed such production. In 2004, a fatal cave-in at Óhegy Park, caused by buried waste atop unstable tunnels, led to major repairs.
By 2012, the district invested 90 million forints to stabilize the area. In recent years, the tunnels have hosted events including guided tours, bike races, underground runs, and diving. Parts have appeared in films, including Spy (2015). The district’s S1 Project envisions transforming the area into a cultural and tourism hub with museums, galleries, and venues. Despite ambitious plans, most of the complex remains quiet, with only a few active uses today. It remains one of Europe’s most complex and underutilized subterranean systems.
Beneath Budapest’s Kőbánya district lies a 35 km (22 mi) tunnel network that began as a 13th-century quarry.
Stretching 30 m (98 ft) deep, this vast space once supplied stone for landmarks, later hid wartime factories, mushroom farms, and now hosts explorers…🧵👇 pic.twitter.com/JyQ6H8yHkY
— Detective Tiger's Stories (@TigerDetective) June 13, 2025