Night Elf workers, called Wisps, want to TBC Classic Gold Entangle a Gold Mine to collect from it, which requires 60 minutes. Once built, Wisps can be'loaded' into the mine, gathering gold without needing to move. Being the ecological sort, they also don't destroy trees while gathering lumber, similar to the other factions. Pop a wisp onto a tree, and it is going to float around gathering lumber for the remainder of the match.
The Undead also have a special gold structure -- a Haunted Gold Mine. Much like Night Elf Wisps, Undead Acolytes remain about the mine and collect mechanically. At 100 seconds, construction one is slower compared to the Entangled Gold Mine, however, Undead Acolytes don't have to stick around in 1 place to build, instead summoning a portal that cheap WOW Classic Burning Crusade Gold attracts their constructions into existence.