the majority have since been converted into flats and the square today is overwhelmingly residential. In early 1963 a surface-level car park was planned for the Brighton Corporation owned central garden; this was changed to a 520-space underground car park, created in 1967-9 using the cut and cover method in which the garden was dug up, the car park with roof constructed, and the lawns and flowerbeds restored. Richard Seifert's , Modernist 24-storey residential block, Sussex Heights, was built in 1968 on land immediately to the east of the square, and was criticised for affecting the character of the square because of its contrasting style and height. During the early 1970s the hotels sought permission from Brighton Corporation to erect neon signs advertising themselves; after negotiation with the Regency Society, a Brighton-wide conservation group formed in 1945, the Corporation made the square and the surrounding area into a conservation area in 1973. Conservation area status gives the council firmer control over planning permission and changes to buildings or street furniture, especially in respect of their effect on "the character and appearance of the area". The original conservation area has since been enlarged twice to its present size of . Architecture Almost all buildings in Regency Square have been designated a Listed building: 47 houses are each listed at Grade II*, while 18 other houses, a memorial, an inn and a set of bollards, have each been given the lower Grade II status. The house at the south west corner is now numbered as part of King's Road, but was built as part of Regency Square and is also Grade II*-listed. The five Grade II* parts of the square, including the house at the south west corner (formerly St Albans House), were listed on 13 October 1952. The entire west side was listed in 1952: St Albans House, the three houses at numbers 2–4 and the sixteen houses at number 5-20. The northern side's central section, numbers 26–37, forms another Grade II* listing. On the east side, all of the surviving original houses, at numbers 51–56, 57–59 and 60–66, are listed at Grade II*. Apart from St Albans House, all of these listings include iron railings attached to the exterior. Numbers 22–25 and 38–46, on the north side, were listed at Grade II on 20 August 1971, while most of the rest of the square's original houses were listed at the