Located in the heart of London's West End, The Londoner is a major new hotel on the world-renowned Leicester Square. The development is situated on a constrained site, bounded on all sides by roads. Planning restrictions limited the height of the building, leading to the development having one of the deepest habitable-grade basements in the world. The basement extends to over 30m deep, with six levels, meaning nearly half of the building's floor area is located below ground. This article provides an overview of the key design and construction considerations associated with building such a deep basement within the heart of London.