the roman habit of putting up notice boards where 3 roads meet (tri via)the notice boards were used to post small pieces of local information amongst other things
According to something I heard today on the radio (I think) the 'tri via' was a point in Rome where three roads met, and it was known as a meeting point for ladies to gossip. The unimportant gossip becamse known as ' the conversation of the tri via' which mutated into 'trivia'.