Brontochion Monastery, Byzantine monastery in Mystras, Greece.

Brontochion Monastery is a Byzantine building in Mystras with two distinct structural levels. The lower level features a three-aisled basilica, while the upper level displays a cross-in-square church crowned by five domes.

Construction of the Hodegetria Church took place between 1310 and 1322, establishing the prototype for a new Byzantine architectural style. This so-called Mystras type influenced religious architecture in the region for generations to come.

The name Brontochion means "thunder" and was shared by both churches of the complex. The Hodegetria's lower walls are covered in marble revetment, a luxury rare even in Constantinople, and above the so-called royal door survives a fresco of the Virgin as Zoodochos Pege, the Life-giving Source. Three inlaid plaques, black, white and violet, remain on the south colonnade's east arch.

The monastery is accessible via marked pathways within the Mystras archaeological site, with entrance tickets available at the main gate. Visitors should wear sturdy shoes since the ground is uneven and the terrain is hilly.

Theodore I Palaiologos, who died in 1407, is buried in the Hodegetria Church, not described as the last despot of Morea. The church's lower walls carry marble revetment, and above the so-called royal door survives a fresco of the Virgin Mary as Zoodochos Pege, the Life-containing Source.