Contrast London's ageing underground with urban transport abroad to work on adjectives, including opposites and comparatives.
Liven up the theme of holidays with a visit to the sewers of Europe. In Rome tourists can see the 2,000-year-old Cloacae Maxima, in Vienna they can follow in the footsteps of Harry Lime, while Paris offers a film, a museum and a short tour. Alternatively, you can visit the Paris catacombs, whose entrance is marked with the words "Arrete. C'est l'empire de la mort".
Include sewage and water in a study of the environment. Ironically, while European directives on the subject emanate from Brussels, the city itself dumps untreated waste in its underground river.