-- London has spent 10 years building the Eiffel Tower, blissfully unaware that they are building one in Berlin and another one in Rome too (after all, Eiffel Towers aren't very big or easy to see are they, very easy to miss one). Suddenly, news comes through that the people of Berlin have built one. Instantly the citizens of London demolish everything they've worked at, somehow convert all that steel to gold and hand it all to the Government.
-- Homer is still alive and well and performing in London
-- on account of Homer's performances, the whole rural northern coastline of France suddenly swaps nationality and becomes part of the UK.
-- but when a big city tries to do the same, it has to ask the UK for permission first. If the UK says no, the city spontaneously implodes and all its inhabitants commit suicide.
-- a city can have half a million inhabitants but noone's thought to build a grocer, hospital, or supermarket there.
-- in an age of nuclear power, every city still needs that old forge to keep its production up
-- despite the best efforts of scientists, sugar, rice and wheat mysteriously refuse to grow anywhere other than the few locations where they were first found in 4000BC
-- the ancient city of Rome spent its first 2000 years with wild horses daily roaming all through its streets but nobody noticed because the emperor's wise men hadn't yet discovered animal husbandry
-- even though you don't yet understand how to build a road or have any written form of communication, you know about the existence of artillery, nuclear power and the possibility of building the Internet, and you know exactly what things you'll need to get your wise men to research and in what order in order to get them.
-- Women's lib came to England, Spain, Egypt and Russia in the year 4000BC. But will never ever spread to any other countries.