The castle was probably built in the 13th century most likely in place of an ancient Estonian stronghold. The bailiwick of Karksi was first mentioned in 1248. The stronghold had a chapel dedicated to Apostle Peter. The first reference was made to a local clergyman in 1298. The present stone church, very simple in design, was built in the same place between 1773 and 1778. St. Peter’s Church is in the ruins of Karksi castle. The tower of the church is leaning, the inclination of the tower’s top is 205 cm at the moment. In 1994 it was decided to save the tower using complicated "construction surgery" developed while stabilizing structures in the old town of Tartu. Eight 10- metre-tall bored piles along with concrete beams penetrating foundations form a new bearing surface for the tower. As a result, the further leaning of the tower has stopped.
On the way which takes you to the stronghold, in the former cemetery of the Knights of the Order of the Sword, stands a nice Baroque chapel among trees, built in the early 18th century by Field Marshal George Reinhold von Lieven, the owner of the Karksi manorial estate. The coats of arms of the Lievens and the Mannteuffels have been fixed to the chapel doors. The chapel, similarly, was built with one side on the former foundation and therefore is somewhat leaning. The buildings of the Karksi manor have perished.
The city walls of Avila were built in the 11th century to protect the citizens from the Moors. They have been well maintained throughout the centuries and are now a major tourist attraction as well as a UNESCO World Heritage Site. Visitors can walk around about half of the length of the walls.
The layout of the city is an even quadrilateral with a perimeter of 2,516 m. Its walls, which consist in part of stones already used in earlier constructions, have an average thickness of 3 m. Access to the city is afforded by nine gates of different periods; twin 20 m high towers, linked by a semi-circular arch, flank the oldest ones, Puerta de San Vicente and Puerta del Alcázar.