Full list of maps in Halo Online Eldewrito
Classic Halo 3 maps:
Guardian
Last Resort (zanzibar)
Narrows
Standoff
The Pit
High Grounds
Valhalla
Sandtrap

Sabre maps, remakes or unfinished maps from bungie/343:
Icebox (Turf remake)
Edge
Reactor
Diamond Back (Avalanche, sand version)