cindy souters, national fish and wildlife ranger on the rocky flats nuclear site transition into a national wildlife refuge. >> so we do have elk that use this area. they use the drainages for calving. we also have mule deer. so there may be some mule deer farms out here. coyotes are other common mammals. occasionally there is a bear in this area. >> and then kimberly field, author of the book "the denver mint: 100 years of gangsters, gold, and ghosts" talks about how the mint changed the city. >> by the 1880s, denver itself had gotten rich from mining. and it wanted to become the queen city of the plains, the center of commerce, the leader in the western united states. and the city fathers at that point decided that a mint they could be proud of was going to be part of that process. >> the c-span cities tour of denver, colorado, saturday at 9:00 eastern on c-span2's book tv. and sunday afternoon at 2:00 on american history tv on c-span3. working with our cable affiliates and visiting cities across the country. >>> u.s. air force academy professor chuck steele teaches a class on the role of