The municipality formed around an abbey founded by St. Trudo, a Frankish nobleman, in the 7th century. After Trudo�s death, the abbey became the centre of a pilgrimage, which brought wealth to the neighbouring town. The 11th century was particularly prosperous and witnessed an important growth in population. This was the time when abbot Adelardus, reporting to the Bishop of Metz, built the abbey�s main church and two additional churches in town: Our Lady (Lievenvrouwenkerk) and Sint-Gangulfus. Under his direction, Sint-Truiden also received an earth wall surmounted by a wooden fence and fortified gates. A proper stone wall, gates and towers, were built in 1129. The economy of this new oppidum city was based on the linen industry and commerce with foreign lands such as England, Champagne, and Germany.
In the 13th century, the fortified town became one of the 23 bonnes villes (main cities) belonging to the Bishopric of Li�ge. A market hall was built at the site where the current city hall stands, the social life of the city was organized by the various guilds, and a perron was erected on the central square, symbolizing the local government�s authority in political affairs.
15th century until now
Charles the Bold captured the town in 1467, marking the beginning of a slow decline that lasted until the 19th century. The city�s fortifications were dismantled in 1675, and many of the religious congregations were disbanded under the French regime at the end of the 18th century. After 1830, these empty buildings were turned into educational and medical facilities. The city was also the centre of a prosperous agricultural region, which from the end of the 19th century became well known for its fruit production.
On August 9, 1914, at the outset of Germany�s invasion of Belgium, 20 civilians were executed and a number of houses destroyed. The reconstruction and building of brand new neighbourhoods accelerated
