Space tourism is only available to very rich people.
Edit by : Cities of EARTH is a free 3D Screensaver which shows biggest cities of our planet.

Features:
Cities
Many of cities with information about its population and country names. So its a good educational content.
The positions of all cities corresponds to its real world coordinates.
Ability to add any city to the Earth map
Ability to disable the displaying of base cities and leave only added by user cities on the Earth map
Daylight and Night time
When you run the screensaver, sunlit part of the Earth is setting according to its real time position (calculated from a local time and time zone on your PC).
Day gives place to a night (and vice versa) very slowly, but if the screensaver is running during a few hours you can notice this.
Displaying of local cities time
Low CPU usage
This 3D screensaver saves CPU time to allowed background tasks to run without appreciable speed losses.
Zoom
Use mouse wheel to MOVE comera closer/farther.
Camera Control
Use up and down arrow keys to control the vertical camera position (e.g. to look at Antarctica).
Use left and right arrow keys to slow down or to speed up the camera rotation speed. you can free download Cities of Earth 3D Screensaver 2.1 now.