Cisternerne – The Cisterns in Søndermarken

From lifesaving reservoir to cultural underworld

Cisternerne lies buried under the grassy slope of Frederiksberg Hill, in the heart of Søndermarken park. Excavation started in 1856 and the immense brick cistern was completed just three years later to help solve Copenhagen’s serious 19th‑century water problems. For decades it could hold around 16 million litres of clean drinking water, forming a crucial part of the city’s early modern supply system. By 1933 the reservoir had become obsolete, and although the structure remained intact underground, it was not fully drained until the early 1980s. In the 1990s, as Copenhagen embraced its role as a European Capital of Culture, the City of Frederiksberg and local curators saw potential in this abandoned piece of infrastructure. The cisterns were gradually reborn first as a glass art museum and later as Cisternerne, a dedicated venue for contemporary art and experimental installations.

An underground cathedral of columns and watermarks

Step below the park and you enter a sequence of long, low-vaulted halls supported by rows of massive pillars. The concrete and brick surfaces still bear the stains and mineral traces of decades under water, giving the space a raw, almost archaeological character. At over 4,000 square metres, it feels at once monumental and strangely intimate, the ceiling never far above your head while the galleries seem to stretch on without end into shadow. The climate is part of the architecture. Because daylight never penetrates, the temperature hovers around 8–10°C year-round and humidity is close to 100%. Underfoot, the floor can be damp or film-thin with water depending on the current exhibition design. The faint echo of footsteps and the occasional drip from overhead reinforce the impression that you are walking through the city’s hidden underbelly rather than a conventional white-cube museum.

Dripstone cave where nature reclaims the structure

Over time, water seeping through the concrete roof has dissolved minerals and redeposited them as delicate stalactites and stalagmites throughout the chambers. These dripstone formations make Cisternerne the closest thing Denmark has to a natural cave, even though it is entirely man-made. Thin, icicle-like fingers hang from beams and edges, while small stalagmites rise from the floor where drops have fallen in the same place for decades. The dripstones are both attraction and warning: beautiful and fragile, yet also evidence of the building’s slow decay. They show how moisture from Søndermarken above steadily infiltrates the structure, blurring the line between constructed space and geological process. Lighting is kept low to protect this environment, so your eyes gradually adapt and begin to pick out the subtle textures of mineral deposits, old brick and reflective pools.

Immersive art tailored to a singular setting

Cisternerne typically hosts one major, site-specific installation each season, inviting artists to respond to the reservoir’s extraordinary scale, acoustics and atmosphere. Works often incorporate sound, fog, light projections or shallow water to heighten the sense of disorientation and discovery as you move through the darkness. Rather than separate galleries, the cisterns form a continuous environment, encouraging you to wander, pause and let each space unfold slowly. Because the venue sits beneath a historic park opposite Copenhagen Zoo and near Frederiksberg Palace, a visit naturally combines with time above ground. Many travellers treat Cisternerne as a cool, contemplative counterpoint to the lively city streets, a place where contemporary art, urban history and a quietly otherworldly setting intersect beneath the lawns and tree avenues of Søndermarken.

Planning your time in the depths

Visits here are self-paced, but most people spend long enough to adjust to the gloom, trace the vaulted chambers and absorb the current exhibition. The constant cool temperature makes it comfortable in summer yet chilly at other times, so bringing an extra layer is sensible even on warm days. Surfaces can be uneven or slightly wet, making sturdy shoes useful. Cisternerne is run as part of the Frederiksberg Museums, with seasonal opening periods and ticketed entry. Simple facilities and information are provided topside before you descend through the glass pavilions that mark the only hint of the vast hidden world underneath Søndermarken.