Beneath Søndermarken, Cisternerne spans 4,400m² across three connected chambers. No daylight reaches the space, and its natural reverberation can last up to 17 seconds. Cisternerne once held Copenhagen’s drinking water. Today, beneath Søndermarken, it remains an underground cathedral of brick arches, untouched by daylight, where a single sound can linger for up to 17 seconds. For one night only, Unearth, a Copenhagen-based platform for experimental music and art, and Strøm, dedicated to electronic music and sound culture, transform the iconic subterranean space into an immersive encounter between sound, light and architecture. Together, they present a newly composed sound work and a site-specific light installation created especially for Cisternerne, drawing on the site’s unique acoustics, darkness and monumental scale. Light traces the vaulted ceilings, while sound moves through the archways, revealing the architecture in new and unexpected ways. It will be a rare opportunity to experience Cisternerne through sound and light in an entirely new way. The composition will play continuously throughout the evening within a site-responsive spatial installation by @unearth.cph, developed in response to the sound work and architecture of the space. Admission to Cisternerne during Culture Night 2026 requires a Culture Pass. From 12 noon on 11 September, the Culture Pass can be purchased digitally via the Culture Night website and shown on your phone on the night. If you prefer a physical Culture Pass, it will be available from all 7-Eleven stores in the Greater Copenhagen area from 28 September.