Any song with a long buildup like Eric Prydz's Opus?

Hi :)

I'm looking for songs similar to Eric Prydz's Opus, mostly regarding the long buildup and the melody that mostly stays constant build becomes more and more intense and complex.

I'm not looking only for EDM, something like Maurice Ravel's Boléro would be great too, and I guess there are some songs like that too in post-rock music.