In which city is the Eiffel Tower?

Paris, and it was built to be demolished. It was the entrance arch to the 1889 World's Fair, licensed to stand for twenty years, and Eiffel's company kept it alive by making it useful - first for meteorology, then for wireless telegraphy. It survived because the army wanted the aerial. It jammed German communications in 1914 and intercepted the message that led to the arrest of Mata Hari.

The Parisian artistic establishment hated it. A petition signed by Maupassant, Dumas the younger, Gounod and others called it a useless and monstrous tower, a black factory chimney crushing the city. Maupassant is supposed to have lunched in its restaurant regularly, on the grounds that it was the only place in Paris from which he could not see it - a story too good to check and repeated ever since.

It is an unusually honest structure. Every one of its 18,000 iron pieces is shaped by the wind load it has to carry, and the curve of the legs is the curve that keeps the wind from producing any bending moment at all. It also grows: the iron expands in summer, and the top can move about 15 centimetres, leaning gently away from the sun as the day goes round.