April 1906. Berlin (Castle Square). At the end of the famous Linden Avenue (Unter Den Linden) and after the Opera Square, you reach the Castle Bridge, over the Sprée. On the other side is the Lustgarten, the former garden of the Castle, today a square 225 meters long by 200 meters wide, where the equestrian statue of Frederick William Iii is located. The Royal Castle is Immediately Found, Founded by the Elector Frederick Ii - Approximate Date