Twin cathedrals-turned-museums (dating to the early 1700s), the Konzerthaus (from 1818, by Carl Langhans) and a row of luxury hotels make up this classic square. The name stems from the mid-1700s when military regiments were stationed here. The Deutscher Dom is home to a museum on the development of the German Parliamentary system, not dull at all if you're a politics buff. You'll have to read German or French to enjoy the exhibit in the Französischer Dom on the contributions of French Huguenots to Berlin's development, beginning in the late 1600s.