Just a few with no specific ranking
Nürburgring 1927, 182 km. First world road race on the very hilly Nürburg Raceway. They had to climb the so called "
Steilstrecke". Only the winner of the race Alfredo Binda could do it on his bike. The rest had to climb off and push. The course was done in 1966 and 1978, too. But without this extremly steep section. But even without it, it's still a very demanding circuit.
Moorslede 1950, 284 km. Not a small circuit, but a bigger one with lots of cobblestones and the Kemmelberg. Briek Schotte simply hammered away and took home his secong world championship.
Solingen 1954, 240 km. Not the longest one, but with a very demanding circuit and really bad weather. Raining the whole day and bitterly cold. The last rounds were every man for himself. Bobet took it in front of Schaer and Charly Gaul.
Frascati 1955, 293 km. Last year freezing cold, this year an extremly hot day in the oven of the alban hills near Rome. Around 35C for the whole day. Race took nearly nine hours.
Salò 1962. 296 km. Again a very hilly and demanding course in big heat. Right at the Lago di Garda. Not a big day for the favorites, neutralizing themselves and so Anquetils best helper Jean Stablinski took it home solo.
Montreal 1974, 263 km. Merckx third victory. Nearly the same course we saw last weekend. The finish line was right after the Mont Royal Climb. It had to be climbed 21 times.
San Cristobal 1977, 255 km. Heavy tropical rains all day, causing nearly every rider to puncture and/or crash. I don't have any information regarding the course. But I guess it was a very hilly one.
Sallanches 1980, 268km . Legend in this sport. Brutal heat and a
brutal climb. Badger time. Only 15 of 107 starters reached the finish line. Hinault simply destroyed everyone of them.
Altenrhein 1983, 270 km. Greg LeMond took his victory on a difficult course with two climbs. A course for big champions.
Duitama 1995, 265 km. Half of the race was pure climbing in 2500m altitude. Unfortunately lots of riders called it off. Only 98 starters, but a world class podium with Olano, Indurain and Pantani.