Originally built in the 15th century by Archduke Siegmund the Rich, the Imperial Palace was rebuilt in Baroque style with Rococo detail by architect Johann Martin Gumpp on the orders of Empress Maria Theresa. The building, flanked by domed towers, has four wings which house state rooms, private apartments and a chapel. Definitely worth a look is the enormous Riesensaal (Giant’s Hall) is a 30 metre long state room decorated with ceiling frescoes, adorned with portraits of the Hapsburgs and embellished with marble and gold; the courtyard is also a wonderful place to visit in the evening.