The Halo 3 Legendary Map Pack is available now on Xbox Live Marketplace for 800 points. To download the maps, go to the Marketplace section of the Start menu (press start in Halo 3 and click “Marketplace”) scroll until you find the Legendary Map Pack and exchange your hard earned wage for the map pack, which contains:
Ghost Town
A medium-sized map designed for one-sided games ideal player counts range from 4 to 10 players. Ghost Town is the battle-scarred remnant of a war-ravaged hydroelectric plant in the foothills of Mt. Kilimanjaro.
Best Gametypes: Team Slayer, One Flag CTF, Multi-Flag CTF, One Bomb
Avalanche
A reimagingation of Halo: Combat Evolved fan favorite, Sidewinder, Avalanche’s size makes it ideal for big ol’ games of Halo 3. Avalanche is a Forerunner power station set on a glacial shelf on an under-construction replacement for Installation 04.
Best Gametypes: Multi-Flag CTF, One Flag CTF, One Bomb, Team King, Team Slayer
Blackout
It's not a reimagination, it's a remake of one of Halo 2's most beloved maps. Blackout very nearly speaks the same language that its predecessor ,Lockout, spoke to Halo 2 players. Its long lines of sight and interconnected platforms preserved, but in a new location: a frigid UNSC research station beneath the low lights of the aurora borealis.
Best Gametypes: Team Slayer, One Flag CTF, One Bomb
LIMITED TIME: For a limited time, purchasers of the Legendary Map Pack will get four months of free access to Bungie Pro -- an expanded File Share for your Halo 3 content. Instead of the standard six slot fileshare, Pro users have 24 slots that they can fill with maps, gametypes, films, clips and screenshots. Within 24 hours of buying the Legendary Map Pack and playing a game on the new maps, your File Share will upgrade to Bungie Pro.
For more on the Legendary Map Pack: