This challenging project involves the construction of a new basement structure beneath the garden of an existing residential property. The subterranean space is designed as an extension to the main house, seamlessly linked via a newly constructed tunnel. The new underground area will be utilized for recreational purposes, featuring a home cinema and a gym.  A Contiguous Pile retaining wall system was employed to form the external perimeter of the basement. A strategically designed connecting tunnel was constructed between the newly formed basement and the existing main house. This tunnel serves as the main access route between the new underground space and the main residence. The internal space of the basement has been thoughtfully divided into a home cinema and gym.