Westminster City Council has approved developer Reef Group’s plans to invest over £150m (US$185.3m, €171.4m) in Cavendish Square, transforming the space into a subterranean mixed-use destination, with a focus on healthcare and wellbeing.

Claimed to be London’s first subterranean health and wellbeing destination, the 280,000sq ft (26,000sq m) destination will deliver specialist facilities for London’s private healthcare sector.

Currently an underground park, the existing structure will be reused and adapted. Wellbeing and sustainability were key in influencing the design with glazed lanterns at street level, internal atria, lightwells and a 200m (656ft) pavement light drawing natural light into all levels of the new development.

Below ground, spaces will range from 5,000sq ft (465sq m) to 250,000sq ft (23,225sq m) and, although no tenants have yet been announced, renderings envisage clinical, spa, fitness and bathing facilities, as well as restaurants, bars and retail space.

Stewart Deering, joint chief executive of Reef Group said: “Reef Group has worked closely with Westminster City Council to design an iconic destination for London and we’re delighted to have secured planning consent for the scheme.

“We’ll invest more than £150m in developing a vibrant, sustainable and sensitively designed place with a core focus on health and wellbeing.

“The scheme is designed with flexibility in mind and we’re talking to occupiers from a variety of sectors. The health and wellbeing industry is predicted to grow substantially and Cavendish Square London is well placed to respond to this trend.”

Construction is expected to start next year with completion in 2023, with UrbanR as the project’s lead architect, supported by Gensler and Sonnemann Toon.