Hanover's Old Town (Altstadt) area is pleasant to explore on foot and is where you'll find the attractive Leine Palace (Leineschloss), the state parliament building.
Constructed in the 17th century on the banks of the river after which it's named, this former royal residence of Duke George von Calenberg was later altered in Neoclassical style between 1817 and 1842.
Just a five-minute walk away across the river is the New Town Church, or Neustädter Kirche, a 17th-century structure with the tomb of the famous German philosopher GW Leibniz, who was buried here in 1716.