in glasgow, where scotland's highest concentration of tenement dwellings can be found, the urban renewal projects of the 1950s, 1960s and 1970s brought an end to the city's slums, which had primarily consisted of older tenements built in the early 19th century in which large extended families would live together in cramped conditions. they were replaced by high-rise blocks that, within a couple of decades, became notorious for crime and poverty. the glasgow corporation made many efforts to improve the situation, most successfully with the city improvement trust, which cleared the slums of the old town, replacing them with what they thought of as a traditional high street, which remains an imposing townscape. (the city halls and the cleland testimonial were part of this scheme.) national government help was given following world war i when housing acts sought to provide "homes fit for heroes". garden suburb areas, based on english models, such as knightswood, were set up. these proved too expensive, so a modern tenement, three stories high, slate roofed and built of reconstituted stone, was re-introduced and a slum clearance programme initiated to clear areas such as the calton and the garngad.