The Real Shadow Wolf on 4/1/2003 at 16:08
I've just been playing Morrowind for a week (being a cheapo, I waited until the price dropped to $30) and my first character is an assassin. I did not hear of the Morag Tong until I found a guild hall in Ald'ruhn. When I requested to join, I was told I'd have to find Eno Hlallu in Vivec. What followed was an all-nighter of searching the cantons of Vivec for the dude. I was getting extremely frustrated until I finally encountered a NPC that told me that the Morag Tong's secret base was below the Arena.
Thought I'd post this hint to spare anyone all the trouble I went to. The base is below the Arena storage area on the west side of the canalworks. There's a trapdoor (trapped) in the floor of the room on the right. This is the access to the base. Once you're in, Eno Hlallu is impressed enough by your ability to find the base to give you a provisional membership pending execution of your first writ.
One other note: At Level 1, my first mark kept toasting me, so I went out into the boonies to level up. Went back for another try at Level 4, and I made quick work of him with a steel flameblade.