Churchill Downs is putting the finishing touches on quarantine and isolation facilities that will house foreign participants set to compete in the 23rd Breeders’ Cup World Championships at the historic track.

The Breeders’ Cup, which features eight championship races with a record $20 million in total purses, will make a record sixth stop at Churchill Downs on Nov. 4. The event made its most recent visit to Louisville in 2000 and this year’s renewal will be the first at the track since the completion of its $121 million renovation in 2005.

United States Department of Agriculture regulations require horses that travel to the U.S. for the Breeders’ Cup to undergo tests to ensure that they are free of diseases that are not present among the domestic horse population. Aside from their training and racing, foreign horses must remain separated from U.S.-based horses during their stay at Churchill Downs.

Churchill Downs’ Barn 45, which contains 38 stalls, has been surrounded by a metal fence and will serve a dual purpose as a quarantine and isolation facility for the visiting European horses during their time at Churchill Downs. In addition, Barn 42–which contains 22 stalls–has been set aside as an isolation facility. Only authorized persons are allowed to enter the fenced areas around those barns