It must have been a great day when they laid all the lintels out in a big circle on the grass to see if it all fitted, like a new train set!
The locating pins are pointed which suggested they were used as .... locating pins. Tricky, getting 40 ton uprights correctly planted, so the shape of the locating pins might allow them a bit of room for error and they could tilt the uprights to make a fit?