The first records concerning the settlement of Třešť date back to late 12th and early 13th centuries, when two major trade routes intersected the Třeštice stream - the Lovětín route, which started in Třebíč and passed through Horní Cerekev to Bohemia and the Humpolec route, which ended in Telč and Slavonice. As a result, Třešť soon become a major trading centre of the region.
A record in the Tables of the Province from AD 1358 mentioned a fortress owned by Záviš of Třešť and Štěpán of Březnice. Subsequently, the fortress was gradually rebuilt and transformed into a castle by a long series of owners starting with Margrave John of Luxembourg, future Czech king and with the owners from the house of Šternberk.
In AD 1490, Václav Vencelík of Vrchoviště bought the castle from Zdeněk Šternberk of Šternberk, together with Třešť village, the adjoining demesne and the villages of Jezdovice and Buková as a gift for his son, Matěj Vencelík of Vrchoviště.
The first records concerning the barons of Vrchoviště, kin of the Smíšek family, with whom they also shared the basic heraldic symbol in their coat-of-arms - the charge of a white unicorn in an azure field - date to the era of last Přemyslids. The family came to the Kutné Mountains with its flourishing silver mining industry and soon the members of the family became Masters of the Mint - i.e. the managers of their own silver mines. It didn't take long before Václav Vencelík became wealthy enough to buy and move into the Žirovnice Castle in 1485 with his entire family. In 1492, Václav Vencelík obtained the title of baron from Holy Roman Emperor Friedrich III. He died in Třešť in 1515, but was buried in Žirovnice.
The Třešť Castle, as the main residence of the family of Vrchoviště since 1513, underwent an interesting series of restorations, as a result of which the lower section of the castle was built in the Gothic style, the first storey in the Renaissance style and the residential section in the Baroque style. A unique wooden footbridge connected the castle with St. Martin's Church, but unfortunately, the footbridge has not been preserved. However, you can still see St. Martin's Church from the windows of the castle and visit it as well.
The first stage of the castle's restoration, managed among others by Italian architects ended in 1564, under the ownership of Kryštov Vencelík of Vrchoviště. The castle was transformed into a four-wing building with corner towers and courtyard arcades and sgraffito-decorated walls. Kryštof Vencelík himself was buried in St. Martin's Church. His gravestone is dated AD 1582.
The barons of Vrchoviště owned Třešť from AD 1490 to AD 1626, when all their property was confiscated on the grounds of their Protestant creed as well as a result of the fact that the last owner of the estate, who fought at the Battle of White Mountain, died without issue.
The town of Třešť flourished under the rule of the Venclíks of Vrchoviště. The Church of St. Catherine of Sienna was built in the town square, as well as a community well and a brewery. A small Jewish community settled in the town and built a synagogue. The most common trades included the manufacture of woollen cloth and timber processing. The tradition of an annual market was likewise established under the rule of the Vrchoviště family.
In AD 1626, the family of Herberstein, counts of Carinthia, became the new owners of the estate.
From 1657 to 1669, the castle was held by the family of Gayer of Edelbach, which had the first storey completely rebuilt, decorated rooms with stucco and paintings and ordered the construction of the main castle portal, as well as building the main tower, and added two fireplaces in today's restaurant and in the antechamber of the convention hall. The tile stoves in the drawing rooms and castle dining rooms, the Mannerist gateway sculptures, two vases at the entry to the castle gardens and the fountain in front of the main castle entrance also come from the 17th century. In 1669, the counts of Herberstein bought the estate back. In the period from 1831 to 1844 the estate was administrated only by appointed officials.
The English park probably dates from the period of 1835 to 1845, since the pictures of the town from before the conflagration of 1824, when 180 houses and the Church of St. Catherine of Sienna were destroyed or damaged by the flames, show only an empty plain in the location of the present park. In the period of 1844 to 1945 the estate was owned by the barons of Wenzel-Sternbach of the Tyrol. In AD 1864, Wenzel von Sternbach was elevated to the rank of knight. In AD 1860, the north side of the castle was rebuilt and the castle facade was situated west. Třešť obtained town status and privileges in 1909.
After 1945, the castle turned into a municipal museum.
The castle, together with the adjoining park (15 ha) became the property of the Academy of Science of the Czech Republic in 1984. After ten years of intensive restoration works, the castle was transformed into a conference centre in 1994.
The oldest preserved historical monument is the Catholic St. Martin's Church, whose construction started in the 13th century and ended in 1593. The church was rebuilt twice, in 1777 and after the fire in 1824. The original Gothic tombstones and stone pulpit and the Renaissance tombstone of Kryštov Vencelík have been preserved to this day.
The Church of St. Catherine of Sienna was built as a German Lutheran church. The presbytery was rebuilt in Baroque style during the 18th century. The interior furnishings come from the 19th century.
The Empire Synagogue was built after a large conflagration, which demolished the Jewish ghetto in 1824. Today it serves as the chapel of the Hussite Church and houses a permanent display of Třešť Nativity scenes.
The historical building in T.G. Masaryk Square acts as the Museum of the Vysočina Region.
Třešť is the birthplace of one of the most influential 20th century economists, the first Austrian Minister of Finance and the father of the Japanese post-war economic miracle, J.A. Schumpeter; exceptional Renaissance astronomer and mathematician Šimon Partlic; the first Pilsen diocesan bishop František Radkovský; and actor Otto Šimánek. The bronze bust of Franz Kafka reminds visitors of the writer's frequent stays in the town in the years 1900 - 1907.
The cobblestones of the main square incorporate the largest functional sundial in the Czech Republic.