Surp Hovanes, Christian church in Mastara, Armenia

Surp Hovanes is a church in Mastara in Armenia's Aragatsotn Province, distinguished by a large central dome supported by four projecting apses arranged in a square layout with inward-curving circular walls. The ground plan combines a rectangular exterior form with rounded interior spaces, creating a distinctive geometric composition.

The church is dated to the 5th century, though three inscriptions by the monk Grigoras, who calls himself its builder, are dated to the 7th century. Study of the masonry showed these refer to a major 7th-century repair, not the original construction. Archaic features support the earlier date: walls 1.30 m thick, horseshoe-shaped apses and arches, large early stone blocks, and a Greek inscription on the oldest course. Repairs continued in the 10th–13th centuries; in 1889 the village priest had the 18th-century walls around it demolished and restored the monument, as recorded on the plaster of the south pier of the main apse.

The church gave its name to the "Mastara-type" churches, a group that includes the 6th-century Voskepar, the 7th-century Mets church of Artik and Harichavank, and the 10th-century Holy Apostles church of Kars. Three inscriptions by the monk Grigoras, who calls himself the church's builder, are preserved on the walls and are dated to the 7th century.

The church stands in the centre of Mastara village, near the town of Talin in Aragatsotn Province, not a few kilometres from Yerevan. Several ancient khachkars are set in the ground around the building, so allow time to walk the churchyard as well as the interior. The thick walls and small windows keep the prayer hall dim, and the dome is lit by eight windows in its drum.

The building merges a square exterior form with completely rounded interior spaces, an unusual architectural feature that sets it apart from most other Armenian churches. This interior rounding creates a surprising spatial experience when entering, contrasting with the strictly geometric exterior.