One of the largest of London's private squares, designed and laid out by John Nash, dominated by plane trees said to have been planted in 1817 to commemorate the allied victory at Waterloo two years earlier. Other trees of note include a tulip tree (Liriodendron tulipifera) and weeping silver lime (Tilia tomentosa 'Petiolaris')
An original and unique feature of the garden is the Nursemaids' Tunnel, an early pedestrian underpass connecting the Square to Park Crescent. The tunnel passes under the busy Marylebone Road, allowing families to promenade safely through both gardens without worrying about the noisy public throng passing overhead.
The combination of Park Square and Crescent was designed to form a transitional entrance feature to Regent’s Park, leading the visitor from the formal Nash streetscape of Portland Place in the south, to the green and picturesque landscape in the north. It was described as a 'sort of vestibule' to the new royal park. New gates and railings have been installed to original designs.
The gardens retain most of their original Nash layout and have been managed continuously from their inception by an organisation specifically set-up in 1824 to carry out this task, the Crown Estate Paving Commission.