areas of Bekkelaget, Nordstrand, Ljan and others south of Ekebergskråningen. It has the best sun conditions and the best views in the city, and it is the furthest away from the industrial area. This is a well-off district, often called "beste østkant" ("the best of the East End"), where the population has the same economic and social features as further west. The formerly working-class areas in the West End, such as Pipervika, Skøyen, Hoffsbyen and Lilleaker, are no longer working-class areas. Geographical and economic differences before 1840 In pre-industrial times, the rich and the poor lived in the same houses, with a wider distribution than what became common after the latter half of the 19th century. In Christiania, the elite lived in Kvadraturen inside the city walls, which were at that time called "Kvartalenerne". This area was the focus of well-off business owners in the East End near Bjørvika, whereas many workers lived in the north-western part along the streets Akersgata, Nedre Vollgate and Øvre Vollgate. The mandatory use of masonry or timber hatch construction (murtvang) was enforced in the area from 1624, and in the early 18th century this use spread out about 200 metres outside the city walls. It was many times more expensive to build houses of masonry than of wood. The mandatory use of masonry, intended to prevent fire hazards, was found difficult to enforce already from 1624, and occasional disputes about it arose as the city grew. In 1766, about 50% of all apartment buildings in Kvadraturen were built of timber hatch, 30% of logs and 20% of masonry. The mandatory use of masonry was one of the reasons that the city became popular among business owners and officials, while low-income inhabitants lived in wooden houses outside the city. The 200-metre boundary caused suburbs to be built outside the city. The decision to spread out the mandatory use of masonry, in 1837, 1844, 1855 and 1858, did not proceed in equal steps with the growth of the city, and wooden suburbs soon rose outside what happened to be the boundary of the mandatory use of masonry at each point of time. The wooden suburbs from the 17th century are gone: Pipervika, Vaterland, Sagene, Grønland, "Oslo" (Gamlebyen). Some of the newer ones are protected and are today seen as attractive places to live: Telthusbakken from the late 18th century and the short street Damstredet from the