The Central Business District (CBD) of Belfast is dominated by the Victorian City Hall (see photograph) which replaced the White Linen Hall in 1903. Planners have made efforts to protect this building from being dominated by high office buildings around it. The Urban Area Plan of 1969, for example, established a zone of 320 metres around the City Hall where no buildings higher than it could be built. The 2001 plan continued this protection.
The other reason for so few high buildings is a geological one. Around 8500 years ago, after the Ice Age, sea levels rose by 20 metres. This led to the deposition of clays in the flooded loughs such as at Larne and Strangford and at Belfast. These clays are locally known as 'sleetch' and, to build upon them requires particularly deep foundations.
Despite restrictions on the height of office blocks, imposed by both geology and planning, there has been an enormous expansion in office space. This had been concentrated on the south side of the city but recent developments have also taken place at Laganside. The development of office space was seen as important in the 2001 Belfast Urban Area Plan and helped to revitalise a city centre which had been threatened by unrest for almost 30 years.
The 'troubles' also had affected retailing in the CBD. In the 1970s security gates had been erected in an effort to reduce the number of car bombs which had targetted many shops and offices. Many retail premises closed as shoppers avoided the city centre. In 1980 over 20% of all retail premises in the CBD were unoccupied. This was a time of construction of out-of-town shopping centres suchas at Sprucefield, near Lisburn, and at Abbeycentre, to the north of Belfast. In the 1970s the rate of decentralisation of retailing was greater in Belfast than in any other British city leading to increased pressure on the suburbs.
Since the ending of the 'troubles', much has been done to revitalise the CBD. There has been pedestrianisation, such as in Cornmarket and accessibility was improved with the construction of multistory car parks. The amount of retail floorspace has increased enormously and a large enclosed shopping complex, the Castle Court Centre, was opened on Royal Avenue. By 1994, the number of unoccupied retail units had fallen to just 2%, a testimony to the resilience of the retail sector.