Berlin has been laid out around its central axis - a long avenue lined by thousands of lime trees linking the royal residence with its hunting lodge. Unter den Linden ("Under the lime trees") is the most famous avenue in the city, created by the Great Elector Frederick William in 1647. Its fine palaces were carefully restored by the former GDR. Despite the major construction work currently underway here, it provides an insight into the history of Prussia and the Empire.