He saw that Venus was growing and waning like the moon, and the geometry of the changing crescent moons must mean that it moved around the sun and not around the earth, which therefore could not be the center of the universe. And there was more evidence of this when he discovered that four moons revolved around Jupiter. He discovered the rings around Saturn. And through his new telescope, Galileo could see that the Milky Way – which to the naked eye appears like a white spot across the sky – actually consisted of countless individual stars. In short, with these telescopes in the hands of one of the most brilliant scientists in the world, our view of the sky has been forever changed.

Museo Galileo: Institute and Museum for the History of Science, Florence (museogalileo.it).

18. The Aztec Sun Stone, Mexico City

Weighing 25 tons and nearly 12 feet in diameter, the Aztec sunstone (also known as the calendar stone) has a place of honor in the National Museum of Anthropology and History in Mexico City. It’s an eye-catching ad. A series of concentric circles are engraved on the circular face of the stone, decorated with complex patterns, symbols and compass-like arrows. In the middle there is a grotesque surface.

It is the most famous relic of Aztec civilization and symbolizes indigenous identity and the nation’s complex relationship with its past. Part of its fascination is that we still don’t know exactly what these carvings mean, why the stone was made, and how it was used. We know that it was made by the Mexican people (rulers of the Aztec Empire) and was only recently installed in Tenochtitlán (now Mexico City) – when Cortes invaded in 1520, killed Moctezuma II and took possession of his empire for the Spaniards.

Many believe that the central figure represents the sun god Tonatiuh. In Aztec cosmology, it represents the fifth sun, or the sun of motion, and is surrounded by representations of four earlier suns (or epochs). Others have argued that the figure represents the earth monster Tlaltecuhtli or another god, Yohualtecuhtli – the lord of the night. But whoever he is, the symbols, rings, and subdivisions in the design around the rest of the stone reflect the Mexica’s 260-day calendar and refer to a millennia-old history.