Several new districts were founded around the city's perimeter, just outside the old fortifications. The largest of these was Friedrichstadt, just south west of the historic core of Berlin, begun in 1688 and named after new Elector Frederick William III, who later became King Frederick I of Prussia. Its street layout followed the Baroque-style grid pattern much favoured at the time, and was based on two main axes: Friedrichstraße running north–south, and Leipziger Straße running east–west. All the new suburbs were absorbed into Berlin around 1709–10. In 1721-3 a south-westwards expansion of Friedrichstadt was planned under the orders of King Frederick William I, and this was completed in 1732-4 by architect Philipp Gerlach (1679–1748). In this expansion, a new north–south axis emerged: Wilhelmstrasse.