High relief in stone
Burgos Cathedral, Spain
This is the way of representing the Trinity that came into use in the 16th century and became standard in the 17th. The Holy Spirit as a dove hovers above the Father and Son. The Son holds the Cross and "is seated at the right hand of the Father," as in the Apostles' Creed. The Father is pictured as an old man. The Son in this example seems a bit older than in many others but is nevertheless clearly in middle age.
Angels flank the Trinity, and the one on the right is probably St. Michael, judging from his sword and military garb.
Read more about the Trinity and about St. Michael.
Photographed at the cathedral by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.