The historical location of the town was a crossroads of the main Livonian routes: on the east-west axis connecting Russia with western Europe, and on the north-south axis northern Estonia with the Latvian territories. The village is first mentioned in a world atlas by the geographer Al-Idrisi in 1154. The scholar mentions the fortress of Viliende belonging at the time to the Estonians of the Skala tribe. This prehistoric stronghold was founded in the 9th century on Kaevumägi Hill (i.e. the location of the later main castle). The first attempt to conquer it by Christian forces took place in 1211, but the siege proved unsuccessful for the crusaders. The defeat of the Estonians did not occur until twelve years later. In 1224, by order of the Master of the Order of the Knights of the Sword Volkwin von Naumburg, the construction of a stone monastic castle began on the site of the conquered fortress, which ten years later became the seat of the commandery (one of six then in existence). Gradually expanded, the Felin stronghold eventually took on the imposing form of a model Teutonic convent castle, consisting of a high castle (to the south) and two lower fortified pre-castles (to the north), also known as the middle and lower castle. The oldest part of the high castle was the massive main tower, the so-called "High Herman", to which a four-winged, two-storey convent house was added on the south-eastern side, housing the most important monastic rooms: among others, the chapel, chapter house, dormitory and refectory. The strategic location of the castle went hand in hand with the rapid development of the settlement, which already had city rights from the second half of the 13th century, and became a member of the Hanseatic League in 1346. Polish ties with Felin began in 1582, when, following the Treaty of Jama Zapolski, the castle and town were occupied by the army of King Stefan Batory. Polish rule over the Livonian fortress lasted less than twenty years, as it was captured by the Swedes in 1600. Two years later, the city was recaptured by the Poles as part of the Livonian expedition of Grand Crown Hetman Jan Zamojski. However, this time too, only for twenty years. As a result of the warfare of the late 16th and early 17th centuries, the city was destroyed and the castle fell into disrepair and lost its military significance.

Modern Viljandi is a town of about 18,000 inhabitants located in the centre of southern Estonia. All that remains of one of the oldest and once most important strongholds of the Order of the Knights of the Sword are picturesque ruins towering over the oblong expanse of Lake Viljandi (4.6 km long). The entire defensive establishment is still legible, the topographical arrangement of the successive hills and the moats dividing them has been preserved, with the division into the former: upper, middle and lower castle. Of the preserved building elements, the following stand out: one of the walls of the upper castle (west), the remains of the castle gate, the lower part of the northern so-called dansker tower and a fragment of the wall of the middle castle. Some elements of the buildings can be identified by the outline of the foundations and a few small relics. The area of the former fortification serves as a walking park, while an amphitheatre with a stage has been arranged on the former high castle, where concerts and open-air events are often held in the summer. An additional attraction on the castle hill is the 50-metre-long rope bridge suspended over a 13-metre-high precipice. The red Art Nouveau construction of the bridge was created by the Riga-based company Felster & Co, in the late 1870s. North of the castle hill in the old town is the post-Franciscan St John's Church (now a Lutheran church). Built in the second half of the 15th century, it is the only surviving medieval monument of the town, despite partial reconstruction. The church is a single-nave building set on an elongated rectangular plan, with a slightly narrower also rectangular three-sided closed presbytery. The main entrance is through a square-shaped porch, which is the base of a tall tower topped with a stylised cupola with a spire. The Old Town is home to the City Museum, founded in 1878. Its current premises, at 10 Johan Laidoneri Square, are housed in an 18th-century building of a former pharmacy owned by the Schöler family, which operated until 1940. The exhibition is divided into three sections: nature, archaeology and the history of the city and the everyday life of its inhabitants. Particularly valuable are the archaeological collections that have been gathered as a result of excavations carried out since the end of the 19th century, including military artefacts from the time of the Livonian wars.