This stone in Lake Geneva was once the reference point used to determine altitude in Switzerland.

The memory of the ancient unit of measurement of local builders.

In this scale model, our neighboring planets are represented by metal spheres spread across an English village. The nearest stars are represented by spheres in California and Australia.

This lesser-known geographic marker was the reference point for all surveys of the continent for 75 years.

The first thermometer made with the almost-universal temperature scale is backwards.

This large copper bolt represents the benchmark for measuring sea levels in most of Europe.

This stone obelisk is a relic of the 17th-century Swedish mile markers.

A monument to the one-armed geologist who led the first documented expeditions through the Grand Canyon.

The former global standard for the exact mass of one kilogram sits under lock and key outside Paris.

This historic system is the zero level benchmark for measuring the depths and altitudes of the Baltic.

The geographical center of Budapest is marked with a 10-foot-tall stylized zero.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

This golfball sized platinum iridium cylinder is the official starting point for all national weight calibrations

An impressive century-old, to-scale topographical map of Guatemala.

Finding the exact middle of a giant land mass is hard to determine, but this spot managed to do the trick.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.