In which country would you find the pyramids of Giza?

Egypt, though the country with the most pyramids is Sudan - around 250 of them, built by the Kushite kings of Meroe, steeper and smaller and far less visited. Giza's Great Pyramid was the tallest structure made by humans for about 3,800 years, until Lincoln Cathedral's spire, which is the longest any record has ever stood.

It is older than almost everything people mentally file alongside it. Cleopatra lived closer in time to the Moon landing than to the building of the Great Pyramid. The mathematics is exact enough to be unnerving: the base is level to within a couple of centimetres across 230 metres, and the sides align to true north to within a fraction of a degree, achieved without a compass, probably by sighting on circumpolar stars.

They were not built by slaves. Excavations from the 1990s found the workers' town beside the site - bakeries, breweries, medical care for healed fractures, and cemeteries where labourers were buried with grave goods in the shadow of the pyramid, which is not how anyone treats slaves. The evidence points to a paid, rotating, well-fed workforce of conscripted farmers, probably working through the inundation season when the fields were under water and there was nothing else to do.