The CHIO equestrian event in Aachen

The Concours Hippique International Officiel (CHIO) has been staged in Aachen since 1923. It is now the biggest horse racing event worldwide and goes on for 10 days every year. The main discipline is show jumping. The two highlights are the Grand Prize of Aachen on the final day and the team competition Prize of Nations.

Another important discipline is dressage, which Germany has long dominated. In 2012, Helen Langehanenberg won the title. Since its inception in 1955, the Dressage Grand Prix of Aachen went to a non-German a mere 15 times. Isabell Werth won it a record eight times.

Horse prodigy Totilas is not taking part in the equestrian festival this year. The 10-million-euro (13 million-dollar) stallion that won the Grand Prix with its Dutch rider Edward Gal in 2010 and with Matthias Rath in 2011 is out of the race. The stud injured his knee while mounting a breeding dummy.

Eventing is particularly interesting as it combines jumping, dressage and cross-country rides. Obstacles are set up both inside and outside the riding arena for the event. Inbetween obstacles, there are also longer stretches for canters and gallops.

Cross-country riding has been under fire because of the high risk of injury for both horses and riders. Animal rights organizations would like to see the discipline banned. Cross-country is also risky for the riders. There have been several fatal accidents, where the rider ended up underneath their horse.

Another discipline is four-in-hand riding, which incorporates dressage as well as obstacle courses and cross-country riding, some of which take place in the woods in Aachen. Riders cross bridges and water. The main rider leads the horses, the other rider stands behind him and uses his body weight to keep the cart balanced.

The newest discipline at the event is vaulting. The horse trots and canters in a circle, the gymnast performs his or her routine on top of the horse, which also involves jumping off the horse and back on it again. Vaulting has its roots in the military as part of the training of the cavalry.

Denmark is the official partner country of the CHIO this year. Crown Princess Mary Elizabeth of Denmark is representing her country at the event. Equestrian sports have a long tradition in Denmark. Its biggest star, Anne Grethe Jensen won the Dressage Grand Prix in Aachen twice in the 1980s.

The world's top 300 riders receive a personal invite to the event, along with their 500 horses. More than 350,000 spectators come to watch the various competitions. In total, there is 2.67 million euros ( (3.5 million dollars) worth of prize money to be won.