I’m currently reading Laurie Lee’s “As I Walked Out One Midsummer Morning” which mentions the Spanish city of Valladolid. Following various Wikipedia links to discover the etymology of Valladolid (unclear) brought me to this site about the Celtiberian language, which I didn’t know till now, existed. It seems it dates to 100 and 200BC and is attested through various inscriptions on excavated bronzes etc.
Apropos of nothing at all except that it happened in Valladolid city library, here’s some flashmob singing worth listening to.
I can recommend the book, btw.
edited in flashmob link