You don't have to have tickets to a concert to check out Red Rocks! The amphitheatre is open to the public most mornings and early afternoons, and there are ample hiking trails to explore as well. Bring sunscreen, there isn't much tree coverage!
16th Street is a walkable pedestrian mall in Downtown Denver with no shortage of attractions, including restaurants, museums, shops, movie theatres, and more! A free mall shuttle is available as well.
We love the Denver Botanic Garden, and not just because it's where Jono proposed! On a nice day, the gardens here are a can't-miss Denver attraction. Though not necessary, we recommend buying tickets online ahead of time.
This is a weird one, and honestly, the less you know going in the better. Think of it as an "immersive and interactive art installation", and know that it is worth it! Though not necessary, we recommend buying tickets online ahead of time.
If you're a baseball fan, Coors Field is worth checking out! It's right downtown and close to lots of bars and restaurants. The Colorado Rockies will play the San Francisco Giants on 5/29 at 6:40 pm, 5/30 at 7:10 pm, and 5/31 and 1 pm. They will probably lose, but who doesn't love a good ball game??
Here long enough for a day trip? Check out the hiking trails at Chautauqua Park in Boulder! You'll be able to see the famous Flat Irons from near and far. After you're done, head to Boulder's Pearl Street pedestrian mall, which has lots of restaurants, bars, and breweries to explore. Boulder is a 45-minute to 1-hour drive from Denver.
Another great day trip idea! Garden of the Gods contains stunning red rock formations as well as easy-to-moderate walking and hiking trails. About an hour from Denver, it is free and open to the public and worth seeing at least once (or approximately 10 times to date if you're Rachel)!