Look for these. Your enemies don't deserve to have them, and you do, so be sure to aggressively fight over such deposits. The largest map available in Age of Empires is the Huge map. This is 200 tiles by 200 tiles. The new Gigantic map, available in the X-Pack, is 250 by 250.
Gigantic maps have a number of interesting effects and one drawback.
If an attack fails to KO your opponent, by the time you reorganize for another attack, he's rebuilt. There are enough fish, berry bushes, and wildlife, that anyone willing to hike for their food may not have to farm till Iron. I personally recommend that if you only have a Pentium 90 with 16 meg, avoid 8 player games on gigantic maps. Even if your machine is reasonably fast, I suggest keeping the pop cap at 50 for more than 4 players on these maps. The computation needed for the computer to figure unit pathing across the gigantic maps becomes a significant time drain when there are too many units on the board.