Clash on the Big Bridge, also known as Battle with Gilgamesh, is the theme of Gilgamesh in FFV. The Black Mages did a version as well, and it also had an arrangement in FFXII.
It's a very good song, but it's also under appreciated. Other then the three "official" versions of the song (the versions from FFV, FFXII, and the Black Mages), I only have one remix of this track. This is probably my favorite FF song, so this saddens me.
The place I can find the MP3 of the original version requires registration, and I'm sure no one likes that, so here are links to the other two versions:
FFXII (Track 313): http://bluelaguna.net/music/final-fantasy-xii-12-ost-soundtrack/mp3s.php
Black Mages (Track 2): http://bluelaguna.net/music/bm/mp3s.php
