Related question: What’s the oldest melody still popular today? A variant of “Greensleeves” was played in Elizabethan England, but I’m sure some Doper can come up with something much older.
Probably the oldest still-recognizable tune is going to be the Dies Irae plainchant sequence which goes back to the early 13th-century. You may not know the name but odds are you’ve heard the tune incorporated into some piece of music or another (classical or popular). It’s never really gone out of fashion.
Given that written Western music (church music, natch) only goes back in any coherent form to the 12th century (see Léonin and Pérotin and the Notre Dame school of polyphony for more details), you’re unlikely to find anything earlier.
I suppose so, yeah. Although, if we’re talking Renaissance vs. Baroque, I don’t know if “maturity” is the right word, when it comes to vocal music. I mean, Palestrina is plenty “mature”, it’s just that he sounds like… well, Renaissance church music. So, it’s about polyphony vs. monody. When Monteverdi does this by the 1630s, it just sounds like a different kettle of fish.
Actually, there is kinda-sorta a term for the “classical in the colloquial sense” that the OP is getting at: The common practice period, spanning about 1600 to around 1900. That covers your Baroque, Classical, and Romantic, more or less.
Edit:
So, by that count, Renaissance is nixed from “colloquial classical”. Which seems about right to me, speaking as an average schmoe.
I don’t know if it counts as “popular,” but “Folia” or “Folie d’Espagne” (wikipedia reference) is pretty darned old, and still has some exposure. It was the title music for Kubrick’s “Barry Lyndon.” (If I’m not mixing up two different ancient themes…)
Thank you! I *love *Beethoven’s Fifth Symphony (the greatest piece of music ever written, IMHO), but I had no idea this theme was incorporated into it! :o
You’re not, and I almost posted that one as well. It’s probably dates to about the same time as Greensleeves or possibly a little later, and has certainly gotten heavy use over the years.
To me classical music is music made with violins (and violas and cellos). Music before violins were invented is something else.
Do you mean that music composed since violins were invented fits the “classical” definition, or only music that actually involves violins?
And what do you call music composed after violins were invented, that doesn’t involve string instruments?
SDMB pedanticism at its very finest!
Actually, the word is “pedantry”.
… Not to be pedantic. 
The latter.
I don’t have a term for that. I was just pointing out that to me classical is synonymous with violins.
Understandable, but of course it doesn’t work as a general definition, because there’s plenty of classical music (including but not limited to big-C Classical music) that doesn’t involve violins (for example, all those piano sonatas and other solo keyboard works), as well as plenty of non-classical music that does (like bluegrass fiddle tunes and pop songs with schmaltzy string accompaniments).
Naxos, a classical music label, put out a box set of a sampling of all eras of classical music. The earliest composer they featured was Hildegarde of Bingen, from the 12th Century. That beats “Greensleeves” by about 400 years.
[quote=“Baker, post:9, topic:757553”]
I love Charpentier. The prelude to his “Te Deum” has been played as a processional at weddings.
[/QUOTE]It was at mine. 