How do you get to the big tower in the oblivion gate near anvil on oblivion PC

i had problems like that as well. i cant remember layout but try these #1, hill climbing, find the big tower, walk towards it until you cant go further, then run around the hill until you find a path up #2 tunnels, walk along whatever paths you can find, go wherever, until you find an oblivion door stuck in the side of the mountain, that'll get you up there