Gefion and Gylfe, situated at Østbanegade 19–21, between Stavangergade and Fridtjof Nansens Plads, is a pair of National Romantic high-end apartment buildings attached to each other by an archway across Mandalsgade in the Østerbro district of Copenhagen, Denmark.

The symmetrical building complex was originally located in the axis of the Langelinie Bridge, an Asger Ostenfeld-designed steel bridge spanning the railway tracks just north of Østerport station, now replaced by a bicycle and footbridge.

The layout of Østbanegade and its side streets was decided in connection with the plans for the new Coast Line in 1893.

Frithjof Nansens Plads was thus originally called Gylfesgade (Gylfe Street).

[2] Gegion and Gulfe are constructed to almost identical but mirrored National Romantic designs.

The two buildings are both constructed in brick with four storeys over a walk-out basement and have a five-bays-long principal facade towards Østbanegade as well as a chamfered corner with a central bay window.

The front side of the buildings are constructed in red brick, faced with granite rustication on the ground floor and the exposed part of the basement and with bands of granite and cement on the upper undressed part.

The two main entrances are accented with decorative granite portals with an oval window and the house number written in gold on the keystone above the arched doorway.

[5] Gefion (Østbanegade 19) was used as a location in the 1963 film Hvis lille pige er du?.