Agios Nikólaos Ragavás, Medieval Orthodox church in Plaka, Greece.

Agios Nikólaos Ragavás is a cross-in-square church with a dome on four columns, standing at the corner of Prytaneíou and Epichármou streets in Plaka. Its walls follow the brick-enclosed cloisonné masonry type, with two dentil bands framing the openings of the north wall. The octagonal Athenian-type dome has eight single-light windows, one per side, and small columns at its corners; two original capitals, a variant of the Corinthian order, survive inside.

The church dates to the second half of the 11th century, built by the Byzantine Ragavas family as a private chapel; some scholars argue for a 9th-century origin linked to Theophylaktos, son of Emperor Michael I. In 1687 a Venetian mortar shell damaged the sanctuary during Morosini's siege of Athens. Repairs in 1833 added a narthex, bell tower and chapel, and restoration in 1979–80 removed plaster to reveal the original dome and north-wall masonry.

The church was originally a private chapel of the Ragavas family, whose best-known member was Emperor Michael I Rhangabes, and later passed to the use of all the city's inhabitants. In medieval Athens it was important enough that both the surrounding district and a nearby gate of the city wall were named after it. The wall paintings seen today were made under King Otto and follow a neoclassical style; the originals do not survive.

The church sits on Prytaniou Street in Plaka and is accessible by walking through the neighborhood's narrow alleyways. The winding streets make navigation simple once you know the location, and the area is pedestrian-friendly throughout.

During the 1979–80 restoration, an engraved invocation was found on a small column of the dome: "Lord, help your servant Leo Rankavas", a rare trace of the family that built the church. The original church was about half the size of today's building.