Flensburg is an independent town (kreisfreie Stadt) in the north of the German state of Schleswig-Holstein. Flensburg is the centre of the region of Southern Schleswig. After Kiel and Lübeck, it is the third largest town in Schleswig-Holstein.

In May 1945, Flensburg was the seat of the last government of Nazi Germany, the so-called Flensburg government led by Karl Dönitz, which was in power from 1 May, the announcement of Hitler's death, for one week, until German armies surrendered and the town was occupied by Allied troops. The regime was officially dissolved on 23 May.

The nearest larger towns are Kiel (86 kilometres (53 miles) south) and Odense in Denmark (92 km (57 mi) northeast). Flensburg's city centre lies about 7 km (4 mi) from the Danish border.

In Germany, Flensburg is known for:

• the Kraftfahrt-Bundesamt (roughly: National Driver and Vehicle Register) with its Verkehrssünderkartei (literally: "traffic sinner card file"), where details of traffic offences are stored
• its beer Flensburger Pilsener, also called "Flens"
• the centre of the Danish national minority in Germany
• the greeting Moin Moin
• the large erotic mail-order companies Beate Uhse and Orion
• its handball team SG Flensburg-Handewitt
• the Naval Academy at Mürwik with its sail training ship Gorch Fock