Once Upon a Time, there was a bosmer named Vytareth ( i.e. created by a then-newbie ESO player ), who set out to explore Tamriel ( initially in the wrong order, thanks to the newbie player being dumped into the game during the Greymoor chapter ). Eventually Vytareth fell foul of the hooded figure, and after many (mis)adventures, ended up at the gates of The Hollow City, talking to the enigmatic Groundskeeper. Being naive and uneducated in the ways of Tamriel, Vytareth had no idea that The Hollow City was full of inconsistencies.

.....

Many years later, an associate ( read; alt character ) of Vytareth, an orsimer named Atuesh Duroel, also entered The Hollow City. Being of a far less naive disposition than her bosmer friend, Atuesh immediately noticed what was wrong with the so-called Hollow City. It wasn't hollow! Inexplicably, there were ogrim chained to carts, ready to transport one to various far-flung parts of Tamriel, for the right price. There were also guild traders near the wayshrine, and occasionally other intrepid adventurers would enter the city.

Personally, I think it would be nice if The Hollow City was initially a solo instance, initially not containing any NPCs or other players, then when the objective "Restore the Hollow City" is completed, The Hollow City transitions to a shared instance, complete with all the usual NPCs, amenities and other players, because having some of these in the city at the start of the zone quest is a bit immersion/quest breaking (to me, anyway).

I have no idea if this is technically feasible, though, because the city would be solo or shared depending on each character's progress through the main quest. Also, its main entrances aren't all blocked by gates, so our characters can freely go through them without any zone transitions.