Denver Botanic Gardens Experience Passes Each pass is good for free admission for up to 6 visitors. Additional guests are subject to general admission fees. Learn more about Denver Botanic Gardens. Share This Twitter Facebook LinkedIn Email Related Posts Denver Zoo Each pass admits up to 4 people (children 2 and under are free). Zoo tickets are date specific. The Colorado Railroad Museum Over 100 locomotives, passenger cars, freight cars and cabooses. The pass admits up to 6 people. Wings Over the Rockies Passes include the Denver Air & Space Museum and the Exploration of Flight Museum in Englewood.