Holy Ghost hole

They were most commonly built in churches in Austria and southern Germany during the Middle Ages and Baroque period, though classicizing architectural elements often replicate their appearance.

[1] Other features of church architecture which are similarly built into the apex of a ceiling or dome, such as oculi, often closely resemble Holy Ghost holes.

[2][3] To symbolise the "tongues of fire" as described in Acts 2:3, burning oakum was often dropped from the hole onto the congregation below.

[6][7][8] Holy Ghost holes are typically decorated with Pentecost motifs, such as doves, rays of light, and flames.

The hole may be permanently left open, displaying a dove figurine or other depictions of the Holy Spirit.