Fort Collins, known for its vibrant culture and outdoor activities, offers numerous free things to do:

1. Horsetooth Mountain Open Space: Enjoy hiking and mountain biking trails with stunning views.
2. New Belgium Brewing Company: Take a free tour of this famous brewery (reservations required).
3. Fort Collins Museum of Discovery: Free admission on select days throughout the year.
4. Gardens on Spring Creek: Explore beautiful gardens and attend free events (donations suggested).
5. Old Town Fort Collins: Stroll through historic downtown, enjoying architecture and window shopping.
6. Poudre River Trail: Bike, walk, or run along this scenic trail following the Cache la Poudre River.
7. Fort Collins Library Park: Enjoy outdoor concerts and events during summer months.

Remember to check official websites or call ahead to confirm current hours and any potential changes to free admission policies.