How do I save a specific iteration of a randomly generated object?

I'm developing a text-based ASCII game and want to be able to save randomly generated objects. For example, if you discover a town, the program will randomly generate a town. Currently however, the game doesn't save the iterations and will simply generate a new town once you leave the screen where the generated town initially appears. What do I need to do to save these objects as a selectable option so that the player may revisit them as they were initially generated?