You go through a portal to the Mages Guild Tower and Lobby, does that count?
If they do, then this is three levels - Lobby, Council Chamber and Archmage's Quarters, all of which are teleport destinations, bit only two of those are
only accessed through a teleport.
It can be argued that the return trip from most of the places mentioned would count. But how many of them are "Tamriel"? Several locations in SI have teleport shortcuts back to locations you already walked to (or could, e.g. in Xedilian).
And just how did I get into this prison in the first place?