Battle Canyon

"Combined with classic multiplayer maps, Enhanced and updated for Xbox LIVE"

—Announcer, Halo: Combat Evolved Anniversary trailer.

Summary
The currently unnamed Beaver Creek remake in Halo: Combat Evolved Anniversary, Is in many ways similar to it's Halo: CE and Halo 2 counterpart, except for minor differences. One example is the fact that the caves on both ends of the river are now entire tunnels, although blocked off by forge-able rocks.

Removing these rocks reveals not only the already mentioned tunnels, but an entire cavern. (as seen in the gameplay videos).

Another example of such changes is the red base. Instead of the entire map being surrounded by rock wall, the back of the red base appears to be blocked off by a huge forerunner machine of some sort.