The Mound
The Mound is the ruin of an ancient city that was destroyed in the Catastrophe. The Mound was once a city called Hoofburg. There are a lot of rough types around the Mound. (F) The Mound was ruined before the Catastrophe, by an industrial accident. Parts are still polluted. (F) An ancient magical-industrial facility in the Mound exploded and produced the crystal forest.
Earthdrop
Earthdrop was founded by survivors from a ruined city called Hoofburg. (F) Earthdrop is so-named because the Earth pony slaves of the first Queen of New Equestria dropped dead unloading her ship there. (Note that this is not only false but stupid; the oceans had fallen by the time that New Equestria had a queen.) Missionaries of the Overseen have been proselytizing in Earthdrop, and their converts are being harassed by the government. (F) Some Followers of the Overseen were martyred in Earthdrop.
Luna City
Luna City was named after Princess Luna during a time of exceptionally good diplomatic relations between Equestria and Ponyland.