One New Street Square is a state-of-the-art corporate headquarters building completed in 2016 and designed by Robin Partington Architects (now known as Apt). The main building contractor was Skanska.
One New Street Square was the world's first building to achieve both BREEAM Outstanding and WELL Gold certifications. The building boasts a biophilic design, incorporating 6,300 plants, 1,500 sq ft of green walls, landscaped terraces, and various other sustainable amenities. The building provides 276,502 sq ft (25,6884.4 sq m) of office and ancillary accommodation arranged over 18 storeys comprising two basement levels, ground, upper ground and 14 upper floors. Two link bridges on the 1st and 7th floors connect the building to the adjacent Two New Street Square. It is fully leased to Deloitte, one of the four largest global accounting firms, on a lease expiring in 2036.