Chapel on the Rock, Catholic chapel in Allenspark, Colorado.

The Saint Catherine of Siena Chapel is a Catholic place of worship built atop a massive rock outcrop near Rocky Mountain National Park. The structure uses the natural stone formation as its foundation, blending architecture with the mountain setting.

A priest discovered this site in 1916 and spent twenty years raising funds before the chapel was completed in 1936. The lengthy planning phase reflects the difficulty of developing such a remote location.

The chapel is officially named for Saint Catherine of Siena and serves as a functioning Catholic chapel open to the public, on the grounds of the Saint Malo Retreat, Conference, and Spiritual Center of the Archdiocese of Denver. Pope John Paul II prayed here in 1993 during World Youth Day and blessed the chapel afterwards.

Visitors can enter the building daily and attend religious services on designated weekdays. The rocky location means stairs or steep paths may lead to the entrance, particularly during snow or icy conditions.

The building survived a devastating fire in 2011 and severe flooding in 2013, while the surrounding retreat center suffered major damage. This resilience made the chapel a symbol of endurance in the area.