The monastery of Panagia Grivitsiani lies in a remote lush ravine between the villages Chomatero and Mistraki in the municipality of Pylos-Nestor. The katholikon is dedicated to the Assumption of Mary (Koimisi Theotokou), although the monastery is more commonly known to the locals by its more recent dedication to Agioi Theodoroi. The main church was probably built in the late 12th – 13th century and is the earliest surviving building of the monastery. A narthex and porches were later added to it. The katholikon underwent a large scale modification in the post-byzantine period, probably just before its re-decoration with new wall paintings in the16th century. Furthermore, it was extended with the addition of a two-storey barrel-vaulted building to its west and a chapel to the northwest.

The church was decorated with wall paintings already in byzantine times, as has become apparent during recent conservation work. Fragments of this early layer were located in various places of the main church. Αfter its renovation in the 16th century, the church was decorated with new wall paintings, made by a group of talented painters. Based on the new evidence, it is likely that this new layer can be attributed to the workshop of the famous Demetrios and Georgios Moschos brothers from Nauplion.