Birdon
This is Birdon, one of the towns from the demo. It was located in a desert area and contains a well, similar to Slowpoke Well.
Goldenrod City (West)
This is Goldenrod City, known as West in the demo.
Olivine Aquarium
This is the exterior of the aquarium at Olivine, known as High Tech in the demo.
Canalave City (New Type)
This is Canalave City, a town that was originally going to appear in Gold/Silver versions, but was later reused in Generation IV, which was Diamond, Pearl and Platinum.
Stand
This is the town that is known as Stand in the demo. It has a zoo and a gym. In the demo, it also had an extra gate that didn't connect to anything.
Kanto
This is Kanto, as it appeared in the demo. Note that the entire region has been shrunk down to just a single town!
Violet City (Old City)
This is Violet City, known as Old City in the demo. Sprout Tower is visible. This town was split into Violet and Ecruteak City in the final game.