Castres (French: [kastʁ] ⓘ; Castras in the Languedocian dialect of Occitan) is the sole subprefecture of the Tarn department in the Occitanie region in Southern France.

It is noted for being the birthplace of the famous socialist leader Jean Jaurès (1859–1914) and home to the important Goya Museum of Spanish painting.

[7] The communauté d'agglomération was created in order to better coordinate transport, infrastructure, housing, and economic policies between the communes of the area.

Castres grew up round the Benedictine abbey of Saint Benoît, which is believed to have been founded in AD 647, possibly on the site of an old Roman fort (castrum).

Following the confiscation of the possessions of Jacques d'Armagnac, duke of Nemours, to which the countship of Castres had passed, it was bestowed in 1476 by King Louis XI on Boffille de Juge (Boffillo del Giudice), an Italian nobleman and adventurer serving as a diplomat for Louis XI, but the appointment led to so much disagreement (family feud between Boffille de Juge, his only daughter, and his brother-in-law) that the countship was united to the crown by King Francis I in 1519.

In the wars of the latter part of the 16th century the inhabitants sided with the Protestant party, fortified the town, and established an independent republic.

Castres was turned by the Catholic Church into an active center of Counter-Reformation, with the establishments of several convents in town, and the building of a renowned bishop's palace by Mgr.

In 1670 however, the Chambre de l'Édit was transferred to Castelnaudary, much to the discontent of even the catholic citizens of Castres, who lost a major source of business and revenue with the departure of the lawyers and the plaintiffs.

In the 1760s, a few years after the famous Calas Affair in Toulouse, Castres made the headlines nationwide: Pierre-Paul Sirven and his wife, both Protestants, were wrongly accused of having murdered their daughter in order to prevent her from converting to Catholicism.

The outbreak of the French Revolution was generally welcomed in Castres, particularly among the local Protestant merchants and entrepreneurs, but the majority of the population remained moderate during the whole period.

In 1793 for instance, Protestant pastor Alba La Source, Castres' representative at the Convention in Paris, opposed the deportation of "non-juror" Catholic priests to French Guiana, where death in the horrid jungle was certain (see Civil Constitution of the Clergy).

Although Castres emerged from the two world wars unscathed, no military operations or combats taking place in southwest France, the local economy has been hard hit by change.

Castres is also crippled by its geographical location, isolated in a dead end at the foot of the Massif Central mountains, away from the main exchange and transport routes.

The creation of the Greater Castres-Mazamet Council in 2000 was expected to deal with the transport problem, and to work on attracting new industries.

The long-promised motorway link with Toulouse is due to be completed soon, and Castres hopes to benefit from its proximity with the big Occitan city.

The principal industries are mechanical and electrical engineering, machine tools, wooden furniture, granite, textile, fur and leather-dressing, tanning, chemicals, pharmaceuticals, and selective breeding of cows.

Castres is the hometown of socialist politician and newspaper publisher Jean Jaurès (1859–1914), who was murdered in Paris the day before the start of the First World War.

Castres possesses the renowned Goya Museum, created in 1840, which contains the largest collection of Spanish paintings in France.

The Jardin botanique Pierre Fabre "La Michonne" is a private botanical garden and conservatory that can be visited.

As one might expect of a town of western Occitania nicknamed Ovalie, the main sport in Castres is rugby union, followed religiously by many locals.