I was fooling around with a song the other day that opened with a C to Ab to C progression, and someone said that it was taken from some composition by Beethoven. Does anyone know if this is true, and if so, what composition?
The common reference here is to Beethoven's Ninth Symphony. The Symphony is in D minor, and alongside its fair amount of D major, there's also a lot of B♭ major. Typically this relationship is best understood as I (or i) moving to ♭VI, not to ♯V.
One reason for this is that the ♭VI relationship makes clear the common tone between the two chords:
In the first two measures, notice how the root of the D chord becomes the third of the ♭VI chord. But in the second two measures, it's less clear that the D becomes the third (now spelled as C𝄪) of the ♯V chord.
I would hesitate to say this was "a Beethoven thing," since other composers, like Schubert, were also playing with these relationships. (In fact, some of Schubert's works are more harmonically adventurous than this Beethoven symphony, and Schubert only died 4 years after it was finished.) But Beethoven's Ninth Symphony is such a towering piece in the history of music that we typically relate this harmonic motion to it.