By cities, I assume you mean places of particular touristic interest, not new cities that have been built as commuter towns to Paris and are just ordinary suburbia.
By train you can reach any of the following in an hour, not counting the travelling time in Paris to reach the correct station ( there are several depending on in which direction you are travelling)
West: Rouen, Giverny, Evreux
North: Beauvais, Amiens, Senlis.
North East: Reims
West: Troyes, Chalon-en-Champagne
South: Fontainebleau, Orleans.
Very close to Paris there is the Palace of Versailles (South) and the cathedral of Saint-Denis (North)which you can get to by ordinary town transport in less than an hour.
If you google any of those places, you will find what are their major attractions.