Illustrated Guide to the world of Spira (FFX and FFX-2)/Lost Cities/Dream Zanarkand
Although it is made clear in the game that the fayth have been dreaming for 1,000 years and that their dream allows Yu Yevon to summon Dream Zanarkand, the nature and the inner workings of this summon are topic of intense debate among FFX and X2 fans. Topics debated include: Where is Dream Zanarkand located, if it is physically in Spira at all, how old the Dream city is (1,000 years of history or just 1 lifetime's worth of history?), how did Jecht get in contact with Sin, etc.
The city we see at the beginning of the game, Tidus' home town, is shown in the game as a very modern city, with little or no magic and no summoners. We can be reasonably sure of that because Tidus does not recognize magic and he is baffled at the term summoner when he gets transferred to Yuna's world of Spira. Tidus does mention when asked that there are only a few fiends in his Zanarkand, but its a big deal when one shows up. We see very few details about Tidus' home town besides the fact that it has a large Blitzball stadium, several large tall buildings, viaducts and a small boat marina.
To Tidus' surprise he learns that the entire city is a dream of the fayth, who are aiding High Summoner Yu Yevon call forth a dream-like version of the Zanarkand that was destroyed 1,000 years ago. The entire city and its residents dissolved into pyreflies after Yuna and her team defeated Yu Yevon.