Eau Rouge/Raidillon, Racing corner at Spa-Francorchamps Circuit, Belgium

Eau Rouge/Raidillon is a corner combination on the Spa-Francorchamps circuit: the track descends into the Eau Rouge dip, bends slightly left, then climbs a right-hand curve with a gradient of nearly 18 percent, rising about 40 metres to a crest where a left kink leads onto the Kemmel straight.

The Raidillon was added in 1939 as a shortcut to raise the circuit's average speed. Until then the track turned sharply left in the Eau Rouge dip and climbed through a hairpin called Virage de l'Ancienne Douane, named for the Belgian-German border post that stood there until 1920. The new layout replaced that hairpin with a right-hand climb of nearly 18 percent.

The name comes from the reddish, iron-rich stream Eau Rouge flowing under the circuit, and raidillon is French for a steep climb. Since 1939 the corner has been a benchmark: Jacques Villeneuve compared racing it to walking a tightrope a metre above the ground, and the 1970 image of Jo Siffert and Pedro Rodríguez climbing side by side in their Porsche 917Ks is still recalled by spectators.

The best viewing spots are from covered grandstands or open grassy areas depending on weather conditions. Visitors should stay alert to safety rules since cars pass at high speeds.

The name comes from the Eau Rouge stream, fed by iron-rich springs that give its water a reddish colour; raidillon is French for a steep climb. Until 1920 the Belgian-German border post stood in the dip, and the old corner there was called Virage de l'Ancienne Douane.