What is the best design for a spaghetti bridge to hold the most weight?

I remember in my HS physics class, the one bridge that killed all the others was a simple arch bridge. It was a sort of roman arch mixed with a Warren that had flat, vertical sides and a flat top with something like half an octagon shape for the arch. It was maybe 2" wide, and used a minimum of spaghetti with several little triangles throughout that resembled scaffolding. The "feet" at each end were roughly 2" X 2". It just sat on top of the desks and spanned the gap, and held ALL the special little weights the teacher had.