Deventer was probably founded around 768 by the English missionary Lebuinus, who built a wooden church on the east bank of the river IJssel. In January 772 the sack and burning of this church by a Saxon expedition was the cause for the first punitive war waged by Charlemagne to the Saxons, in which, in retribution, the Irminsul (sacred tree) was destroyed. This was not the first human settlement at the location; between 1981 and 2006, remains of a Bronze Age settlement (dated to c.400 CE) were excavated at Colmschate, 4 km east of the current city
The village of Deventer, already important because of a trading road crossing the river IJssel, was looted and burnt down by the Vikings in 882. It was immediately rebuilt and fortified with an earthen wall (in the street Stenen Wal remains of this wall have been excavated and restored).
Deventer received city rights in 956, after which fortifications were built or replaced by stone walls around the city for defense. Between 1000 and 1500, Deventer grew to be a flourishing trade city because of its harbour on the river IJssel, which was capable of accommodating large ships. The city eventually joined the Hanseatic League.
One of the commodities it traded in, dried haddock and cod from Norway, gave the citizens the nickname they carry to this day: "Deventer Stokvis" In the 15th century, Deventer had a common mint, where coins for the three IJssel cities Deventer, Zwolle, and Kampen were made.
Deventer is the birthplace of Geert Groote and home to his Brethren of the Common Life, a school of religious thought that influenced Thomas a Kempis and Erasmus in later times. Together with Haarlem it was among the first cities to have printing presses, dating back to as early as 1477. From around 1300, it also housed a Latin School, which became internationally renowned, and remained in service in changing forms until 1971. Its most famous pupil was the scholar Desiderius Erasmus, who was born in 1466 and attended the school from 1475 to 1484.
- The Waag (Weighing-house) on the edge of the Brink square, built in 1550 and restored in 2003. The Deventer City Museum is housed inside the Waag. The Museum's collections include industrial and trading history, paintings by Gerard Terborch and Han van Meegeren, silver objects, and prehistoric findings). Thea Beckman's novel Het wonder van Frieswijck ("The Frieswijck Miracle") features the Waag.
- On the outer wall of the Waag hangs a large kettle that is over 500 years old, said to have been used for a public execution in the late Middle Ages; a man who had produced counterfeit coins was cooked to death in it. According to local tradition,There are holes in the kettle shot by footmen of Napoleon's army around 1809.
- The Saint Lebuinuskerk (St. Lebuin's Church) in Gothic style, with remarkable ceiling paintings and a beautiful organ. Its tower can be climbed in summer.
- The Brink (market square) with houses, shops, and cafes dating from 1575-1900. The market square is also the center of Deventer nightlife. Alongside this square there is the Bussink "Koekhuisje", where you can buy the famous Deventer Koek (honey-cake). Markets take place every Friday (including a very big one on Good Friday, following a medieval tradition) and Saturday.
- The Speelgoedmuseum (Toy Museum) behind the Waag, housed in one of the most picturesque old houses of the city.
- The medieval Bergkerk (Mountain Church), on top of a small hill (old river dune), now a museum for modern art.
- The picturesque and old streets around the Bergkerk, known as Bergkwartier (Mountain Quarter) situated on and around an old river dune.
- The Stadsarchief en Athenaeumbibliotheek (City Archive and Athenaeum Library), the oldest scientific library of the Netherlands (founded in 1560).
- De Proosdij in the Sandrasteeg is the oldest stone house of the Netherlands still in use. The earliest parts dating back to around 1130.