Which musical piece is this from Code Geass? This tune is from R2 episode 23, near 19:20 mark in the version I have, though it is played many times in the series. 

The tune plays at 7:15 in this video.

Does anyone know which musical piece this is?
It's an unreleased piece from the soundtrack called Path of Decisions. You can find it here:

Code Geass: Unreleased Album - 30 Path of Decisions