I found an open set of large gates not for from Stendarr's Beacon But I got a message saying you cannot go that way and even with the NoClip cheat I was only able to go just past the gates then got stopped again.

I read somewhere on the net that a guy said he had gone nearly to Tamirel this way ?

Isn't that out of the game world? I had a similar experience just past the ruined tower (forgot the name) near Traitor's Post in the NE.

Isn't Tamriel the whole place... including Skyrim etc ? Woops, nitpicking

I found that yesterday. Was wondering where it went myself.

Good point, from what I read this guy had gone nearly all the way to { It had Tamriel but I suppose they meant Morrowind } but I couldn't get very far past the gate even with Noclip but you could still see the road going off into the distance

The whole continent is called Tamriel. Skyrim is a province within Tamriel, and the locale for the events in the game.