This suited astronaut was spotted amongst the animals and saints decorating the outer wall of Salamanca’s Ieronimus Cathedral, built in 1102 AD.
As viewers of the Indianpad site have pointed out, the stone from which he is carved looks much newer than its surroundings, so rather than being a 1000-year old time traveller, we can guess that his image was added sometime in the past four decades.
More images at Indianpad blog
Thanks Jack Sarfatti!