It will soon be Meydan Racecourse in the United Arab Emirates - they're constructing it now. http://www.gizmag.com/dubai-to-build-worlds-biggest-racetrack/9165/ and http://www.meydan.ae/ might be good resources on that.
There's no specifics for a horse racing track. Horse race track dimensions vary according to the style of racing, the distances and the type of events as per the country's racing code.
a horse who does well on a muddy track
There is Golden Gate Fields, which is a horse racing track, but that is in Oakland, which is not far from San Francisco.
It opened in 1864.
Yes, technically there is a horse racing track in Laredo Texas. It is called Laredo Race Park, it is a class 2 racetrack. It is licensed, but has not been constructed yet.
Great Leighs racing track is situated in a village in the county of Essex,England.
the pentagon
Usually none.
You race around a track in a horse and cart
A horse track is a place where people race horses in competition. There are a few different races that are held on the track, harness racing, flat racing and steeple chasing. Here is a good website to help you understand more about horse tracks. http://en.wikipedia.org/wiki/Horse_racing
Horse racing memorabilia is available at many major race track gift shops. Horse racing memorabilia could also be found at antique shops and pawn shops.
3200m figure 8 horse racing track by Karra.