Until 1737, the city fortifications erected from 1658 to 1683 are torn down and replaced by a 14.5 km customs (excise) wall. It contains an area covering 1,330 hectares with a population of 80,000. This area remains almost unchanged until 1841.
Starting in 1740, Berlin develops into a center of the Enlightenment and of constant construction under Friedrich the Great. The large representative buildings put up in this era still dominate the cityscape around Unter den Linden: the Armory (Zeughaus, completed already in 1707 – photo), the Palace of the Crown Prince (Kronprinzenpalais, 1732), the Opera Palace (Opernpalais, 1737), the Staatsoper opera house (1742), the Prince Heinrich Palace (Prinz-Heinrich-Palais, 1756, now Humboldt University), St. Hedwig’s Cathedral (1773), and the Old Library (Alte Bibliothek, 1780).