Berlin's magnificent boulevard, the centrepiece of the Old Berlin, leads from Pariser Platz at the Brandenburg Gate to the Schlossbrücke bridge. Unter den Linden was originally a bridle path: from 1573, it led from Berlin Palace to Lietzow, later Charlottenburg, and then on to Spandau. From 1701, the Linden became more and more built up, mirroring the rising splendor of the monarchy and the new architectural style.
As time went by, the Zeughaus (Arsenal) and the Friedrichstadt appeared; under Frederick the Great, they were joined by the Kronprinzenpalais, the Prinzessinnenpalais, the Opera House and the Palace for Prince Heinrich, now the Humboldt University. The Forum Fridericianum, begun at the end of the 18^th century, was to be the intellectual and artistic centre of the monarchy, with the Staatsoper, the Academy Library, St. Hedwig's Cathedral and, on the opposite site, the Palace of Prince Heinrich.
Schinkel's great architectural achievement was the unification of the various buildings and styles into a single aesthetic concept: this led to the creation of the Neue Wache (New Guardhouse), the Schlossbrücke bridge and the redesigned Lustgarten; in this way, Unter den Linden became a coherent ensemble. At the end of the 19^th century, the Berliner Dom was constructed in the eclectic Wilhelmine style.
During the Second World War, Hitler ordered the linden trees to be chopped down so that the road could be widened and integrated into the east-west axes; by the end of the war the avenue was a wasteland of ruins. Those buildings which still stood were gradually reconstructed, but the real work of rebuilding, which included the demolition of the Stadtschloss (Berlin Palace), only began in earnest in 1958. Sleek, 1960s buildings with uniform façades began to appear. The place of the former Berlin Palace was taken by the Palast der Republik (Palace of the Republic) which had to be closed in the nineties due to its intoxication with asbestos. Since the Fall of the Wall, many buildings have been restored and reconstructed. The Lustgarten, previously used as parade grounds, has been redesigned as a garden in accordance with Lenné's plans.