Chur is the capital and largest town of the Swiss canton of the Grisons and lies in the Grisonian Rhine Valley, where the Rhine turns towards the north, in the northern part of the canton. The city, on the right bank of the Rhine, is reputedly the oldest town in Switzerland.

The official language of Chur is German, but the main spoken language is the local variant of Alemannic, known as Grisonian German. Romansh and Italian are significantly spoken in the city as a result of the trilingual identity of the canton.

On 1 January 2020 the former municipality of Maladers merged into Chur and on 1 January 2021 Haldenstein also merged. On 1 January 2025 the former municipality of Tschiertschen-Praden merged into Chur.

Archaeological evidence of settlement at the site, in the Eastern Alps, goes back as far as the Pfyn culture (3900–3500 BC), making Chur one of the oldest settlements in Switzerland. Remains and objects from the Bronze and Iron Ages have also been found in the eastern sector of the centre of the current city. These include Bronze-Age Urnfield and Laugen-Melaun settlements from 1300 to 800 BC and Iron-Age settlements from the 5th to 3rd centuries BC.

The Roman Empire conquered the area that then came to be known as the Roman province of Raetia in 15 BC. Under emperor Diocletian (late 3rd century AD), the existing settlement of Curia Raetorum (later Chur) was made the capital of the newly established province of Raetia prima.

In the 4th century Chur became the seat of the first Christian bishopric north of the Alps. Despite a legend assigning its foundation to an alleged British king, St. Lucius, the first known bishop is one Asinio [de] in AD 451. The bishop soon acquired great temporal powers, especially after 831 when his dominions were made dependent on the Empire alone.

After the invasion of the Ostrogoths it may have been renamed Theodoricopolis; in the 6th century it was conquered by the Franks. The city suffered several invasions, by the Magyars in 925–926, when the cathedral was destroyed, and by the Saracens (940 and 954), but afterwards it flourished thanks to its location where the roads from several major Alpine transit routes come together and continue down the Rhine. The routes had already been used under the Romans but acquired greater importance under the Ottonian dynasty of the Holy Roman Empire. Emperor Otto I granted the town the right to collect tolls in 952 and appointed his vassal Hartpert as bishop of Chur in 958, giving the bishopric further privileges. In 1170 the bishop became a prince-bishop and kept total control over the road between Chur and Chiavenna.

In the 13th century the town had some 1,300 inhabitants and was surrounded by a line of walls. In the 14th century at least six fires damaged or destroyed the monasteries of St. Luzi [de] and St. Nicolai [de] and St Martin's Church [de] and twice destroyed much of the town. The Gotteshausbund (League of the House of God) was formed in 1367 in Chur to resist the rising power of the Bishopric of Chur and the House of Habsburg. Chur was the chief town of the League and one of the places the League's assemblies met regularly. A burgomaster (mayor) of Chur is first mentioned in 1413. The bishop's residence was attacked by the inhabitants in 1418 and 1422, when a series of concessions were wrung out of him.