Use a ruler to find out how long your paces are in metres.

Now work out how many paces you would need to make to walk along one side of the two biggest pyramids (about 220m).

In a large park, step out the paces you need, then look back to see how far you have come. Now look up half as far as you have walked. That is where the top of the pyramid would be (about 136m or 446 ft - one and a half times the height of St Paul's Cathedral, London).