Even Falangia began to wonder if it was a good idea to follow the twins by now. This wasn't teaching anymore. This was pure torture! However, the twins were both in the Elemental Transformation Realm, so escape was impossible!
The area of a city should really be in kilometers^2.
Anyone with cultivation below the Saint Realm was prohibited from flying inside the city. That being said, Rean's group had to walk to reach their destination. Of course, with the city being larger than 1000 kilometers, running would take them way too long.