I added the below caption and image to the Trombone History Timeline, 16th century.
c. 1510—Torrijos, Spain: Above the front door of the Colegiata del Santisimo Sacramento de Torrijos is a pair of trombones with slides crossed (see below image; public domain). Special thanks to Elies Hernandis Oltra.
Christian Goldsmith
Excellent! Why particularly were trombones chosen as a motif here, do you know?
It would be interesting to know if the trombone was significant to this order.
Do you know much of Spanish liturgical or indeed any Spanish music for trombone of this time?
wkimball
Honestly, I don’t know. Possibly an allusion to music, or particularly to sacred music.