Agios Stefanos (, meaning Saint Stephen) is a town and a northern suburb of the Athens agglomeration, Greece. Since the 2011 local government reform it is part of the municipality of Dionysos, of which it is the seat and a municipal unit. The municipal unit has an area of 8.136 km2.

Geography

Agios Stefanos is situated in the hills in the northeastern part of the Athens conurbation, at about 350 m elevation. It lies east of the Parnitha mountains, northwest of the Penteliko Mountain, and 4 km southwest of the Marathon Reservoir. The source of the river Kifisos is near Agios Stefanos. It is 9 km west of Marathon and 21 km northeast of Athens city centre. Its built-up area is continuous with those of the neighbouring suburbs Anoixi and Stamata to the south. The A1 motorway (Athens–Thessaloniki–Evzonoi) passes west of the town. Agios Stefanos has a railway station on the railway from Athens to Thessaloniki. Athens ERA-1 transmitter, the second tallest man-made structure of Greece, is situated north of Agios Stefanos.

Historical population

Agios Stefanos has historically been an Arvanite settlement.