An early concept document explains the ideas behind the project:
We want to bring home the human scale of events and places in history. The Apollo 11 Moon walk explored an area smaller than Trafalgar Square; the distance between your WW1 trench and the enemy could only be as much as from your front door to the street corner.
Dimensions is a feature on websites that juxtaposes the size of historical events with your home and neighbourhood. You’re hearing about the span of the base of the Great Pyramids, or the distance of the book depository from JFK, or the extent of the Great Fire of London… Dimensions overlays this map on a satellite view of where you live.