I was discussing this idea in the dev chat, but was told to make a proper thread to discuss it.
The Propylon stuff was a bit confusing and somewhat useless in Morrowind. While it would become even more useless with fast travel activated, I think we could make them a little more user friendly anyway. Surely some people will disable fast travel or just want to experience Morrowind without it.
The Dawnguard expansion had these little gazebo things that, once activated, could be used to travel to various parts of the 'vale'.
You can go here at 4 minutes 41 seconds to see one of these dome things being activated, and how the interior looked.
What I propose is that we base our concepts for the propylon concepts off this model. It comes with animations and the doorway system already in place. One challenge will be making the gazebo 10 sided, with doors enough for passageways to all the stronghold complexes.
The gazebos will start out as inactive, like the dome. Instead of an Auri-El statue thing, there will be a spot for the player to place the respective index. When the player places the correct index into the receptacle the dome shall rise, revealing the gazebo of doors, and this location will now be accessible from any other 'active' Propylon chambers.
The door opposite the entrance for a given Propylon chamber will have a large map of Vvardenfell with a 'you are here' ping, and the name of that stronghold written in Daedric so the player can know where they're going when traveling through the gazebo thing.