The date and circumstances of the town's foundation are unknown. Tradition maintains that Braunschweig was created through the merger of two settlements, one founded by Bruno II, a Saxon count who died before 1017 on one side of the river Oker – the legend gives the year 861 for the foundation – and the other the settlement of a legendary Count Dankward, after whom Dankwarderode Castle (Dankward's clearing), which was reconstructed in the 19th century, is named. The town's original name of Brunswik is a combination of the name Bruno and Low German wik, a place where merchants rested and stored their goods. The town's name therefore indicates an ideal resting place, as it lay by a ford across the Oker River. Another explanation of the city's name is that it comes from Brand, or burning, indicating a place which developed after the landscape was cleared through burning. The city was first mentioned in documents from the St. Magni Church from 1031, which give the city's name as Brunesguik.

In the 12th century Duke Henry the Lion made Braunschweig the capital of his state and built the Cathedral of St. Blasius. He became so powerful that he dared to refuse military aid to the emperor Frederick I Barbarossa, which led to his condemnation and fall.

Braunschweig was a member of the Hanseatic League from the 13th century to the middle of the 17th century. In the 18th century Braunschweig was not only a political, but also a cultural center. Emilia Galotti by Lessing and Goethe's Faust were performed for the first time in Braunschweig.

Braunschweig was at times one of the residences of the rulers of the Duchy of Brunswick - Lüneburg, which was a constituent state of the Holy Roman Empire until 1806 and of the German Empire from 1871. At the end of World War I the Duchy became the Free State of Brunswick within the Weimar Republic.

During World War II thousands of forced Eastern workers were brought to the city. During the years 1943 – 1945 at least 360 children taken away from the workers died in the Entbindungsheim für Ostarbeiterinnen.

In World War II, Braunschweig was a Sub - area Headquarters (Untergebiet Hauptquartier) of Military District (Wehrkreis) XI. It was also the garrison city of the 31st Infanterie Division, which took part in the invasions of Poland, Belgium, France, and Russia, and was largely destroyed during the German withdrawal from Russia. The city was severely damaged by Anglo - American aerial attacks. The air raid on October 15, 1944 destroyed most of the Altstadt (old town), which had been the largest ensemble of half - timbered houses in Germany, as well as most of the churches. The Cathedral, which had been converted to a National shrine (German: Nationale Weihestätte) by the Nazi Government, still stood.

After the war, Braunschweig ceased to be a capital when the Free State of Brunswick was dissolved by the Allied occupying authorities (most of its lands were incorporated in the newly formed state of Lower Saxony). The Cathedral was restored to its function as a Protestant church. The rebuilding of the city was intended to make it modern and automobile oriented. A small section of the Altstadt survived the bombing and remains quite distinctive. In the 1990s efforts increased to reconstruct historic buildings that had been destroyed in the air raid. Buildings such as the "Alte Waage" (originally built in 1534) now stand again in their pre - war glory.

The Burgplatz (Castle Square), comprising a group of buildings of great historical and cultural significance: the Cathedral (St. Blasius, built at the end of the 12th century), the Burg Dankwarderode (a 19th century reconstruction of the old castle of Henry the Lion), the Neo - Gothic Town Hall (built in 1893 – 1900), as well as some picturesque half - timbered houses, such as the Gildehaus (Guild House), today the seat of the Craftsman's Association. In the center of the square stands a copy of the Burglöwe, a Romanesque statue of a Lion, cast in bronze in 1166. The original statue can be seen in the museum of Dankwarderode Castle. Today the lion has become the true symbol of Braunschweig. The Altstadtmarkt ("old town market"), surrounded by the old town hall (built between the 13th and the 15th centuries in Gothic style), and the Martinikirche (church of Saint Martin, from 1195). The Kohlmarkt ("coal market"), a market with many historical houses and a fountain from 1869. The Magniviertel (St Magnus' Quarter), a remainder of ancient Braunschweig, lined with cobble - stoned streets, little shops and cafés, centered around the 13th century Magnikirche (St Magnus' Church). Here is also the Rizzi - Haus, a highly distinctive, cartoonish office building designed by architect James Rizzi for the Expo 2000. The Romanesque and Gothic Andreaskirche (church of Saint Andrew), built mainly between the 13th and 16th centuries. The church was heavily damaged in World War II, and is expected to enter into its final stage of restoration in 2009 after some sixty years of intermittent work. The Gothic Aegidienkirche (church of Saint Giles), built in the 13th century, with an adjoining monastery, which is today a museum. The "Herzog Anton Ulrich Museum", a well known art museum and the oldest public museum in Germany (founded 1754). The Staatstheater (State Theater), newly built in the 19th century, goes back to the first standing public theater in Germany, founded in 1690 by Duke Anton Ulrich. The royal palace of Braunschweig was bombed in World War II and demolished in 1960. The exterior was rebuilt to contain a palace museum and shopping center, which opened in 2007.

The city has an inexpensive and extensive 35 km electric tram system. First opened in 1897, it has been modernized, including a 3.2 km extension in 2007. The system is unique as the only European railway or tram system to use the 1100 mm gauge, this being supplemented with in stages with a 1435 mm third rail, to allow future connections to the main railway network.

Many other geographical locations are named after Braunschweig such as New Brunswick in Canada due to the personal union of the Duchy of Hanover with Great Britain from 1714 to 1837 (see House of Hanover, also referred to as the House of Brunswick, Hanover line).

Braunschweig has been an important industrial area. Today it is known for its University and research institutes, mainly the Johann Heinrich von Thuenen Institute, until the end of 2007 named Federal Agricultural Research Centre, and the Physikalisch - Technische Bundesanstalt (PTB). The PTB Braunschweig maintains the atomic clock responsible for the DCF77 time signal and the official German time. The region of Braunschweig is the most R&D intensive area in the whole European Economic Area investing 7.1% of its GDP for research & technology. Braunschweig was named Germany's City of Science 2007 (German: Stadt der Wissenschaft 2007).

Also located in Braunschweig is the "Martino - Katharineum", a secondary school founded in 1415. It had such famous pupils as Carl Friedrich Gauss, Hoffmann von Fallersleben, Richard Dedekind and Louis Spohr. Since 2005, Braunschweig has an international school.

Lower Saxony's only university of art, founded in 1963, can be found in Braunschweig. Its German name is "Hochschule für Bildende Künste Braunschweig".

Braunschweig is the home of two piano companies, both known worldwide for the high quality of their instruments: Schimmel and Grotrian - Steinweg (cf. Steinway). Both companies were founded in the 19th century.

Braunschweig is famous for Till Eulenspiegel, a medieval jester who played many practical jokes on its citizens. It also had — and still has — many breweries, and still a very peculiar kind of beer is made called Mumme (Braunschweiger Mumme), first quoted in 1390, a malt extract that was shipped all over the world.

Near Braunschweig at Cremlingen - Abbenrode, there is a large medium wave transmitter, which transmits the program of "Deutschlandfunk" on 756 kHz, the Cremlingen transmitter.

The Braunschweig Airport (BWE / EDVE) is located north of the city.

Braunschweiger liverwurst is named after the city.

The Braunschweig Classix Festival is an annual classical music festival. It is the largest promoter of classical music in the region and one of the most prominent music festivals in Lower Saxony.

Sandberg Guitars headquarters is in Braunschweig.

Braunschweig's local football team is Eintracht Braunschweig. Founded in 1895, the club can look back on a long and chequered history. It won the German football championship in 1967. Despite playing the German 2nd Soccer division now (2011 - 2012 season), the club still attracts a large number of supporters.

The Braunschweig Lions is the city's American football team, seven times German Bowl Defender and two times Eurobowl champion.