This is it. The line. That brass strip running across the courtyard is the Prime Meridian — zero degrees longitude — and it is the single most agreed-upon line on the surface of the Earth. Stand across it, one foot each side, and you are standing in the eastern and western hemispheres at the same time. Everything east of your right foot is measured in degrees east. Everything west of your left is degrees west. This is the seam of the world, and you can stand on it.
But why HERE? Why is zero in a London suburb and not Paris, or Rome, or anywhere else? Because in eighteen eighty-four, the countries of the world held a conference in Washington to pick one single starting line for the whole planet, so that maps and clocks would finally agree. And they voted for Greenwich, largely because most of the world's shipping already used Greenwich charts anyway. Britain won. And one country took it very, very badly. France had lobbied hard for the line to run through Paris, and losing the vote wou
nded them so deeply that, for decades afterward, France flatly refused to use the word "Greenwich." Instead — and this is real — they defined their national time, in law, as "Paris Mean Time, retarded by nine minutes and twenty-one seconds." Which is, if you do the arithmetic, exactly Greenwich time. They would rather describe the entire world's time as a specifically delayed version of Paris than
