The City Tower of Deln is a huge, imposing structure. It is impossible, stretching upwards into the sky. The stone it is cut from appears to be sandstone, but shows minimal erosion whilst giving off the sense of incredible age. The work looks primitive yet incredibly precise. As you approach it, you realise several things - it is not a single tower, but four individual towers linked over and over by bridges throughout, allowing a traveller to pass between any of them. The other thing you realise is you are looking at at a corpse. There is no movement, no sound, no smoke, no light, no smell. You are looking at the skeleton of a beast coming up from the sands, a relic of time immemorial.
The interior of the towers is unsettling - incredibly urban yet also alien in every element. There is no understandable logic to the tangle of what appears to be residential rooms, commercial areas, gardens, temples, offices, storehouses, corridors, manufacturing areas, restaurants, barracks, training rooms, forests, natural caves and other impossible contents. Furniture and goods are perfectly preserved, and every shop contains honesty-boxes for payment. Every item is labelled with name (always readable) and price (always in your preferred currency) yet there are no residents.
Not a single creature is found, though there is evidence of similar expeditions to your own - camp-fires, expended ammunition, refuse. Eventually you will encounter groups or individuals similar to your own - lost, trapped or eager explorers. Some will be hostile. Some will have long ago given themselves to Deln. Some will attempt to live in this place as the residents did, replacing goods which have been bought, growing food in the gardens and forests, living in the beds. Over time, they will describe, the urge to leave diminished. They grow to love Deln. They would attack those who seek to destroy Deln. They only live above the tenth floors. There is nothing to stop anyone leaving apart from themselves. You will not always come out where you entered.
There are battles fought in the upper levels between those who now live in Deln, though all involved are very careful to not damage the city. There will be those from outside your reality here. There will be cultures from your past and future here. It would seem Deln has always been deserted, a place of squatters. It would also seem Deln is able to be found anywhere by those who seek it. However, Deln is masked from divination magic, and from the sight of the gods. The journey is the important thing. Clerics attempting to contact their gods in Deln are stonewalled, but spells are granted as normal. However, when they are cast, they seem dusty, as if retrieved from some ancient archive and then delivered, rather than granted in the normal way.
Everyone who knows of Deln speaks of it's great treasures. No-one knows how tall Deln is. They speak of the dangers of Deln. No-one knows who built Deln or why. It is said Deln will fall when the end comes.