Below elegant Søndermarken Park lurks Copenhagen's damp, dripping 19th-century reservoir. These days it's best known as Cisternerne, one of Copenhagen's most unusual and atmospheric art spaces. Each year, a renowned artist is given the opportunity to transform the reservoir into a huge, immersive installation. Artists have included Denmark's Eva Koch and German-born Christian Lemmerz, as well as Japanese architect Hiroshi Sambuichi. See the website for current exhibition details.