| 50 km|| German autobahns|
| Schleswig-Holstein, Lower Saxony (planned)|Bundesautobahn 21 Wikipedia
Bundesautobahn 21 (translates from German as Federal Motorway 21, short form Autobahn 21, abbreviated as BAB 21 or A 21) is an autobahn in Germany.
It runs from an interchange with the A 1 at Bargteheide to Wankendorf, halfway between Bad Segeberg and Kiel. A northbound extension to Kiel and a southbound extension connecting to the A 250 are being planned. The A 21 will cross the extension of the A 20 near Bad Segeberg.