The city of Sigulda has done a fine job developing the historic buildings at its core into one unmissable complex. The highlight is the Livonian Order Castle, which was constructed between 1207 and 1209 by the Livonian Brothers of the Sword. Its evocative ruins are being restored and are worth an exploration. Some sections are complete and you can walk along the ramparts and ascend a tower with wonderful views over the forested Gauja Valley.
See if you can spy Krimulda Manor and Turaida Castle poking through the trees.
At the front of the complex, the 1878 neo-Gothic manor house was the home of Russian prince Dimitri Kropotkin, the man responsible for turning Sigulda into a tourist haven. It now houses Sigulda district council and is not open to the public. The complex's grounds have some lovely gardens; historic auxiliary buildings are now home to excellent restaurants, cafes and shops with working artists.