When the Las Vegas Monorail first opened, it was a free transportation system between the MGM Grand Las Vegas and Bally's Las Vegas, then known as the MGM Grand-Bally's Monorail. The MGM Grand-Bally's Monorail utilized two Mark IV monorails purchased from Walt Disney World for $3.5 million each: Coral and Lime. These two trains were built entirely by WED Enterprises in 1985, using the original Martin Marietta blueprints. When the system was extended as the Las Vegas Monorail in 2004, these Mark IV trains were retired in favor of a fleet of new Mark VI trains from Bombardier. These trains, while built on the existing Mark VI platform developed for Walt Disney World, are different in physical appearance, are shorter, and are completely automated.