At some ten kilometers from the heart of Niğde there is a now well-advertised monastery hewn in a rock face that has many other dwellings (there is a small bus each hour, a taxi is not expensive though - but hard to find for the return trip). I visited first in 1992, when is was easy to reconnoitre the terrain, but taking pictures inside was hard because of lack of light. So I returned in 2019. Note that if you check on websites there is a fair chance you'll see pictures of Sumela in Trabzon province, much larger and totally different (and hundreds of kilometres away).

The monastery is carved out of a large rock and is one of the best preserved and largest of its kind in the Cappadocia region. There are quite a few monasteries hewn out of the rock in Cappadocia and some scholars split these into two types: those with dining halls and those with open courtyards. The Gümüşler Monastery is part of the second group. The most important part of the monastery complex is the church to its north. The church comprises of four freestanding closed ails based on the Greek cross plan; in the northern aisl of the cross there is a niche with two tombs . To the west there are two entrances covert with a cradle vault. The function of many of the other spaces in the monastery is not known.
It is assumed that at least three different masters worked on the paintings found on the walls of the church. In the main apse there are three bands of paintings: the highest shows Christ Enthroned with two angels to his right, the symbols of the gospel writers and the moment of Desis with Mary and the disciples. The lowest series shows fathers of the church, Basil the Great of Kayseri, Gregory of Nisa, Gregory of Nazians and the like.
In the north aisle of the cross are representations of The Annunciation, The Nativity and The Presentation at the temple with the figures of John the Baptist in Saint Stephen which must have been painted by the hand of a second artist. On the inside of the narthex to the south of the entrance door are representations of Mary and baby Jesus and on each side of them the archangels Gabriel and Michael which belong to the hand of a third artist.
On the walls of a room above the narthex is an example of something not seen anywhere else in Cappadocia: hunting scenes. There is an interesting composition of a variety of animals. The special style and iconography of the paintings on the walls of the Gümüşler Monastery is the same as that be seen in many churches in Cappadocia. It is possible to date the paintings in the church to the 12th and 13th century A.D. by comparing in evaluating them by these traits.
Source: Niğde. Booklet by the T.C. Niğde Valliği II Kültür ve Turizm Müdürü, Niğde / 2017 ISBN 978-605-359-445-0 with texts in Turkish and English (this text almost verbatim, a few typing errors corrected).