From the Introduction:
The Gallery of Dreams?
Yes, of course I've heard of that strange place. The mages say that Grey the Diviner had an apprentice once, a young mage named Temarath. He supposedly cared more for the history of the world than the future of the world and so Grey showed him how to capture the dreams of the past.
You don't believe that story?
Well perhaps you'll believe this one. They say that the goddess, Talishia of the Dream Well, paid Mor Aldenn a visit once and made a pact with the mages. If they would protect her greatest secret, she would keep and protect the dreams of the City of Mages.
Rumors persist that there is an art gallery unreachable by any street, unmarked by any sign and putting on display art that has never been seen anywhere else in the world. The rumors are, for the most part, true. It appears seemingly at random locations within the city that are forgotten or rarely traversed. Sometimes the portal will manifest at a corner shop on a slow street, at other times it will manifest as a backdoor to a building that previously lacked it and in at least one incident the portal manifested in a wardrobe belonging to an unsuspecting apprentice mage. Those who enter may stay as long as they like and leave whenever they choose. However, the moment the visitors leave the gallery the door slams shut and the portal vanishes to inconspicuously appear at another location.