Autovía B-21

{{short description|Motorway in Spain}}

{{Expand Spanish|topic=transp}}

{{Infobox road

| country = ESP

|province = B

| type = Autovia

| route = B-21

| alternate_name =

| maint = Ministerio de Fomento

| map =

| map_notes =

| length_km =

| terminus_a = Autovía A-2, Autovía B-20

| terminus_b = Port of Barcelona

| junction =

| e-road =

}}

The Autovía B-21 is a Spanish motorway that is an access road to the Port of Barcelona from the A-2 and the B-20 (Ronda de Dalt).{{Cite web|url=https://www.fomento.gob.es/recursos_mfom/pdf/30286D08-ED54-46A3-947E-8DCABA54478C/69708/0140100_2004.pdf|title=NOMENCLATURA Y CATALOGO DE AUTOPISTAS Y AUTOVÍAS|publisher=Ministerio de Fomento}}