Most of the roads in Ireland, at least for my 'Murrican sensibilities. My wife and I took our honeymoon in Ireland and rented a car to get around. Aside from driving on the opposite side of the road, we were unprepared for how narrow all but the main highways were. The typical road there is comparable to a small country road here, is often lined with hedges right up to the edges, and often lacks a center line. The sheer terror of going past a large truck going the opposite way on one of those for the first time was very, very memorable. We eventually got used to it, but that first day or two of driving was definitely white-knuckled.