When people hear “Dijon,” most immediately think of that golden, spicy condiment that graces sandwiches around the world. And yes, this city in the heart of France is indeed the birthplace of Dijon mustard—but Dijon is far more than just a spread.

In a quiet patch of green above the River Thames, not far from the bustle of London, lies a hilltop that quietly commands the world’s time. This is the Royal Observatory, Greenwich—home of the Prime Meridian, keeper of Greenwich Mean Time (GMT), and arguably the most important line on Earth that you’ll never actually see in daily life... but absolutely can *stand on* here.