Question: When did the roof gardens above the city where the Albert Memorial and Royal Albert Hall is located open to the public?

full_context: Document 1: Department store: The design and function of department stores in Germany followed the lead of London, Paris and New York. Germany used to have a number of department stores; nowadays only a few of them remain. Next to some smaller, independent department stores these are Karstadt (in 2010 taken over by Nicolas Berggruen, also operating the KaDeWe in Berlin, the Alsterhaus in Hamburg and the Oberpollinger in Munich), GALERIA Kaufhof (part of the Metro AG). Others like Hertie, Wertheim and Horten AG were taken over by others and either fully integrated or later closed.
Document 2: London: In the dense areas, most of the concentration is via medium- and high-rise buildings. London's skyscrapers such as 30 St Mary Axe, Tower 42, the Broadgate Tower and One Canada Square are mostly in the two financial districts, the City of London and Canary Wharf. High-rise development is restricted at certain sites if it would obstruct protected views of St Paul's Cathedral and other historic buildings. Nevertheless, there are a number of very tall skyscrapers in central London (see Tall buildings in London), including the 95-storey Shard London Bridge, the tallest building in the European Union.
Document 3: London: The Monument in the City of London provides views of the surrounding area while commemorating the Great Fire of London, which originated nearby. Marble Arch and Wellington Arch, at the north and south ends of Park Lane respectively, have royal connections, as do the Albert Memorial and Royal Albert Hall in Kensington. Nelson's Column is a nationally recognised monument in Trafalgar Square, one of the focal points of central London. Older buildings are mainly brick built, most commonly the yellow London stock brick or a warm orange-red variety, often decorated with carvings and white plaster mouldings.
Document 4: Department store: All major cities have their distinctive local department stores, which anchored the downtown shopping district until the arrival of the malls in the 1960s. Washington, for example, after 1887 had Woodward & Lothrop and Garfinckel's starting in 1905. Garfield's went bankrupt in 1990, as did Woodward & Lothrop in 1994. Baltimore had four major department stores: Hutzler's was the prestige leader, followed by Hecht's, Hochschild's and Stewart's. They all operated branches in the suburbs, but all closed in the late twentieth century. By 2015, most locally owned department stores around the country had been consolidated into larger chains, or had closed down entirely.
Document 5: London: The largest parks in the central area of London are three of the eight Royal Parks, namely Hyde Park and its neighbour Kensington Gardens in the west, and Regent's Park to the north. Hyde Park in particular is popular for sports and sometimes hosts open-air concerts. Regent's Park contains London Zoo, the world's oldest scientific zoo, and is near the tourist attraction of Madame Tussauds Wax Museum. Primrose Hill in the northern part of Regent's Park at 256 feet (78 m) is a popular spot to view the city skyline.
Document 6: Neues Schauspielhaus: While the auditorium was destroyed in World War II, the facade as well as the cinema survived and in 1951 was renamed the Metropol. Since 1977 it has been used as a discothèque and became a famous music club during the 1980s heyday of West Berlin, frequented by bands like Depeche Mode, Morrissey, The Cross, The Human League and Front 242. For a short time in 2000 it was the location of the KitKatClub and in 2005 the architect Hans Kollhoff remodeled the interior as the "Goya" night club.
Document 7: London: London contains four World Heritage Sites: the Tower of London; Kew Gardens; the site comprising the Palace of Westminster, Westminster Abbey, and St Margaret's Church; and the historic settlement of Greenwich (in which the Royal Observatory, Greenwich marks the Prime Meridian, 0° longitude, and GMT). Other famous landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Paul's Cathedral, Tower Bridge, Trafalgar Square, and The Shard. London is home to numerous museums, galleries, libraries, sporting events and other cultural institutions, including the British Museum, National Gallery, Tate Modern, British Library and 40 West End theatres. The London Underground is the oldest underground railway network in the world.
Document 8: South Bank Lion: The South Bank Lion, also known as the Red Lion, is a Coade stone sculpture of a standing male lion cast in 1837. It has stood at the east end of Westminster Bridge in London, to the north side of the bridge beside County Hall, since 1966. Painted red between 1951 and 1966, the paint was later removed to reveal again the white ceramic surface underneath.
Document 9: London: London's buildings are too diverse to be characterised by any particular architectural style, partly because of their varying ages. Many grand houses and public buildings, such as the National Gallery, are constructed from Portland stone. Some areas of the city, particularly those just west of the centre, are characterised by white stucco or whitewashed buildings. Few structures in central London pre-date the Great Fire of 1666, these being a few trace Roman remains, the Tower of London and a few scattered Tudor survivors in the City. Further out is, for example, the Tudor period Hampton Court Palace, England's oldest surviving Tudor palace, built by Cardinal Thomas Wolsey c.1515.
Document 10: Kensington Roof Gardens: The building housed the department store Derry and Toms until 1973, and then Biba until 1975. Since the 1980s the garden has been used as a restaurant and club.
Document 11: London: London is home to many museums, galleries, and other institutions, many of which are free of admission charges and are major tourist attractions as well as playing a research role. The first of these to be established was the British Museum in Bloomsbury, in 1753. Originally containing antiquities, natural history specimens and the national library, the museum now has 7 million artefacts from around the globe. In 1824 the National Gallery was founded to house the British national collection of Western paintings; this now occupies a prominent position in Trafalgar Square.
Document 12: Plymouth: In 2004 the old Drake Circus shopping centre and Charles Cross car park were demolished and replaced by the latest Drake Circus Shopping Centre, which opened in October 2006. It received negative feedback before opening when David Mackay said it was already "ten years out of date". In contrast, the Theatre Royal's production and education centre, TR2, which was built on wasteland at Cattedown, was a runner-up for the RIBA Stirling Prize for Architecture in 2003.
Document 13: Imperial College London: Imperial's main campus is located in the South Kensington area of central London. It is situated in an area of South Kensington, known as Albertopolis, which has a high concentration of cultural and academic institutions, adjacent to the Natural History Museum, the Science Museum, the Victoria and Albert Museum, the Royal College of Music, the Royal College of Art, the Royal Geographical Society and the Royal Albert Hall. Nearby public attractions include the Kensington Palace, Hyde Park and the Kensington Gardens, the National Art Library, and the Brompton Oratory. The expansion of the South Kensington campus in the 1950s & 1960s absorbed the site of the former Imperial Institute, designed by Thomas Collcutt, of which only the 287 foot (87 m) high Queen's Tower remains among the more modern buildings.
Document 14: Department store: All the major British cities had flourishing department stores by the mid-or late nineteenth century. Increasingly, women became the major shoppers and middle-class households. Kendals (formerly Kendal Milne & Faulkner) in Manchester lays claim to being one of the first department stores and is still known to many of its customers as Kendal's, despite its 2005 name change to House of Fraser. The Manchester institution dates back to 1836 but had been trading as Watts Bazaar since 1796. At its zenith the store had buildings on both sides of Deansgate linked by a subterranean passage "Kendals Arcade" and an art nouveau tiled food hall. The store was especially known for its emphasis on quality and style over low prices giving it the nickname "the Harrods of the North", although this was due in part to Harrods acquiring the store in 1919. Other large Manchester stores included Paulden's (currently Debenhams) and Lewis's (now a Primark).
Document 15: Department store: The middle up segment is mainly occupied by Metro Department Store originated from Singapore and Sogo from Japan. 2007 saw the re-opening of Jakarta's Seibu, poised to be the largest and second most upscale department store in Indonesia after Harvey Nichols, which the latter closed in 2010 and yet plans to return. Other international department stores include Debenhams and Marks & Spencer. Galeries Lafayette also joins the Indonesian market in 2013 inside Pacific Place Mall. This department store is targeting middle up market with price range from affordable to luxury, poised to be the largest upscale department store. Galeries Lafayette, Debenhams, Harvey Nichols, Marks & Spencer, Seibu and Sogo are all operated by PT. Mitra Adiperkasa.
ground_truth: 1980s
sub_queries: Where in London are the Albert Memorial and Royal Albert Hall located? Answer: in Kensington
when did the roof gardens above in Kensington open to the public Answer: 1980s