London
London, founded by the Romans, burnt to the ground by Queen Boadicea, rebuilt and subsequently reburnt in 1666 is a fascinating city, as center of the British Empire is accumulated the wealth of the colonies and other conquered nations. And sometimes it accumulated some of the wealth from rather dubious means, for example the Elgin Marbles which are in the British Museum. Much of London dates from after the fire in 1666 but some areas escaped damage unscathed, the Tower of London built originally for William the Conqueror in 1080 and still in use to this day, as well as Westminster Abbey built from 1245 to 1512.
Travel Tip: Londoners may complain about it, but really the tube (subway for us people on the west side of the pond, a subway in London is what we call an underpass) is the best way to get from points A to B. With the new congestion charge and lack of parking it is probably the cheapest way except for a bicycle, and if you can withstand the onslaught of rush hour crowds you'll do fine in the world's oldest subway system, some of it seems to have NEVER been upgraded since it was first built for horse drawn trains. Actually if you have a chance take the new Jubilee Line, modern, clean and spacious.
Yorkshire
York is a fascinating city, founded by the Romans as Eboracum, Constantine was proclaimed emperor of Rome in 306AD, later on the Vikings took over, stayed, raised families and renamed the city to Jorvik from which the current name derives. In the nearby Marston Moor (11 km west of York) Oliver Cromwell defeated the last remaining royalists in 1644. York is one of a few remaining walled cities in England, it's cathedral built from 1220 to 1472, is the largest in northern Europe also features the largest stained glass window from medieval times. Much of the city within it's walls dates from this period up to the 1600's.
Paris
Travel Tip: Asides then getting lucky with Easyjet and getting a flight to Paris for 1 pound, typically to get a cheap fare on the EuroStar normally involves staying in Paris for a Saturday, another way if your travel plans don't permit a Saturday stay is take the Eurostar to the Marne-la-Vallee-Chessy (Disneyland Paris) station and take the RER train to Paris.