In 1898, German civil engineer Nicholas von der Nonne developed the first professional plan for the growth of Baku. In the early 1960s, during the term of Baku mayor Alish Lemberanski, the city's micro-regions (suburbs) were created outside of Baku, and old, crumbling buildings gave way to Soviet-style architecture. Narrow streets were widened into boulevards to accommodate more vehicles. In April 1960, as part of the festivities during the 40th anniversary of the Soviet Union, a walking tour was arranged to show the Soviet leader Nikita Khrushchev a brand-new walkway made of colorful blue and pink concrete slabs. In fact, Khrushchev never saw the walkway, but typical buildings of this period are still called "khruschovki", from Russian: хрущëвки.