Unter den Linden at the heart of the historic section of Berlin developed from a bridle path laid out by Elector John George of Brandenburg in the 16th century to reach his hunting grounds in the Tiergarten. It was replaced by a boulevard of linden trees planted in 1647, stretching from the city palace to the gates of the city, by order of the “Great Elector” Frederick William. While the western part of the boulevard retained its character, the area around present-day Bebelplatz was changed after the Thirty Years' War and fortified. There are no trees.