Greenwich is most known for hosting the Prime Meridian but also located
here is the Royal Naval Academy, shown here in the foreground.
The buildings in the back across the river are Canary Wharf

Located up the hill is the Royal Observatory

The Royal Observatory was commissioned in 1675 by King Charles II

These buildings house one of the greatest scientific institutions ever

This is the marker for the Prime Medidan, which is 0 degrees of longitude

At is also marked by this strange pointer in front of the building

Besides Time, the observatory was important for weights and measure
Here we see official representations of measures like the British yard
Unfortunately for the Brits, the Meter is somewhat more important :)