which resulted in many summertime residences being built around Stockholm. But the booming urban development was also notable in central Stockholm where several prominent Neo-Renaissance buildings were built, including the Academy of Music and Södra Teatern. In 1866, a commission led by Albert Lindhagen produced a city plan for the ridges (malmarna) designed to offer citizens light, fresh air and access to Swedish nature by mean of parks and plantations. To this goal, he proposed a system of esplanades culminating in Sveavägen, a 2 km long and 70 m wide boulevard inspired by Champs Elysées. 1877–80 new city plans were finally passed for central Stockholm, which made the city well-prepared for the major expansion that followed. During the 1880s more than 2.000 buildings were added on the ridges and the population grew from 168.000 to 245.000. At the end of the century, less than 40 per cent of the residents were born in Stockholm. While this demand for housing was mostly dealt with by private entrepreneurs who built on pure speculation, street width and building heights were strictly regulated by the new city plans which ensured the city that evolved was given a uniform design. A trend initiated by the Bünsow House at Strandvägen, the 1880s saw many monumental brick buildings evolve, including Gamla Riksarkivet and the Norstedt Building on Riddarholmen. Before the end of the decade, most new buildings were equipped with electricity and telephones were increasingly common. During the 1890s, the Neo-Renaissance plaster architecture was replaced by structures in brick and natural stone, largely inspired by French Renaissance architecture. Around what still was factories outside the customs of Stockholm, shacks whose sanitary conditions defied all description evolved. Before the end of the century, however, these were transformed into municipal societies, which facilitated regulation of health and construction, and by the turn of the century, the expansion had continued far beyond the city limits, with villa suburbs initiated by individuals adding a mix of purely speculative structures and more qualitative ambitions. The new century saw the introduction of Art Nouveau with the Central Post Office Building by Boberg (1898–1904) and Neo-Baroque with the Riksdag (1894–1906). Throughout the 1910s, trams were electrified and cars were rolling on the streets of Stockholm. During this period, Stockholm further developed as a cultural and educational centre. In the 19th century, a number of scientific institutes opened in Stockholm, for example the Karolinska Institutet.