Oat Hill Mine Trail follows 8.3 miles of an old stage couch route between Calistoga and the western end of Aetna Springs Road in Pope Valley over an elevation change of 1500 feet. The trail can be divided with the halfway point at the base of the Palisades (Holms Place) with a return to Calistoga or on to Pope Valley with a car shuttle to return you to your original location (it takes two hours to complete the round-trip car shuttle). Construction of the Oat Hill Mine Road was started in 1873 to provide a transportation route between Calistoga and the cinnabar and quicksilver (mercury) mines. It took 20 years to complete the project and the road was officially opened in 1893, and connected Calistoga to the Oat Hill Mine with a side branch descending to Aetna Springs. Today the 8.3-mile-long Oat Hill Mine Trail follows the original route between Calistoga and the western end of Aetna Springs Road in Pope Valley. The old mercury mines are further to the north, and are not open to the public. The trail provides a magnificent recreational experience for hikers, mountain bicyclists and equestrians, although the trail is rough and rocky in many places, and can be quite challenging. Visitors can enjoy sweeping views of Napa Valley along the lower Oat Hill Mine Trail, while the middle and upper sections of the trail cross striking volcanic formations. The trail passes through a diverse mixture of Oak, Douglas Fir, Gray Pine and Cypress forests, chaparral, and grasslands. Spring wildflowers are exceptional. Midway along the trail is the homestead property of Karl Gustov Holm, who built a log cabin on his 160-acre homestead in 1893, and added a new house in 1896. Parts of stone wall for his barn and a few old fruit trees remain today. Ruts carved by heavy wagons traversing the soft volcanic rock are still visible along parts of the middle and upper trail. Hand-laid stone walls are visible at many locations along the trail.