I once heard this taken even further, believe it or not.
The width of the roman war wagons that set the width of the tracks, subsequent wagons and then the railroad tracks was designed to allow for two roman war horses pulling.
This track width was transferred to the US where it dictated the size of a tunnel. This tunnel happened to be on the railroad between where they manufactured the rocket nozzles for the space shuttle and Cape Canaveral. The rocket nozzles vere dimensionally limited so that they'd be able to get through this tunnel.
Thus, the design of the space shuttle was determined by the width of the behind of a roman war horse.
True or not, it's sort of amusing.
Cheers,
/ft