Set amid open countryside near the rural hamlet of Old Knebworth in Hertfordshire, this remarkable five-bedroom house was built on the site of a disused above-ground water tank. It radiates ergonomically around a majestic central tree-like core from which its three levels and sweeping irregular roofline are suspended. Designed with handcrafted natural materials and sustainability at the forefront, it extends over 4,820 sq ft, with generously proportioned spaces for living and working. Despite the secluded feel, the house is within easy reach of Cambridge, St Albans and under 30 minutes by train from London King's Cross.