While researching another topic on Google Earth I came across an amazing sight... this very expensive, over-engineered monster of a rotary (rotante in Italian) in Catanzaro, Calabria. Rotaries in Italy are commonplace and (believe it or not) are simple to use, unlike the "circles" as we call them in the States, where everyone tries to jockey for position entering or exiting the "circle", cutting across lanes and causing fender benders all over the country. They are not for timid drivers.
But in Italy, the rotary is one of the few things Italian engineers and Italian drivers got right. I never had a problem going around one. The exits and entrances are simply and clearly marked, for the most part they are single lane (except for the big one in the photo above) and drivers slow down when entering and give leeway to the car entering first. It's a smooth flow of traffic around them.
They are also are also usually built at ground level with simple engineering and similar layouts... pretty much every rotary looks like every other one. There are no surprises when entering and the signs for the roads coming from them are clearly marked. The elevated highway rotary in Catanzaro is the first massive one I've seen... and the first elevated 75 feet into the air on all sides!