The Romans have been using it since the days of Julius Caesar, but not to get high. Washington and Jefferson grew it. Now that several states have legalized the use of marijuana for some recreational and medical purposes, one of the biggest untapped markets for the cannabis plant — at least one variety — could be as a building tool. The most sustainable building material is not concrete or steel — it is fast-growing hemp. Hemp structures date to Roman times. A hemp mortar bridge was constructed in the sixth century, when France was still Gaul.
Source: Bend Bulletin