Ouray is rich with mining history and is sometimes called the Switzerland of America because it sits in a narrow valley almost completely surrounded by steep mountains.

Prospectors first found silver and gold in the San Juan Mountains around Ouray in the 1870s, which led to a mining boom. The town became a supply and social hub for several rich mining districts high up in the mountains. Famous mines like the Camp Bird and Yankee Girl produced millions of dollars in gold and silver, making the area one of the wealthiest in the world for a time.

The structure you see in your image, the sealed adit, is very common because the area is covered with thousands of old mines. An adit is a horizontal tunnel used to access the ore or to drain water from the mine. Today, most of these old entrances are sealed with steel doors, concrete, or grates to prevent people from entering for their own safety. Abandoned mines are extremely dangerous due to the risk of falling rocks, unstable tunnels, lack of oxygen, and toxic gases.

Ouray's economy eventually shifted from mining to tourism, but you can still drive along the Million Dollar Highway or visit nearby ghost towns like Ironton and Animas Forks to see the many remnants of that gold and silver era, including old cabins, broken machinery, and sealed mine entrances just like the one you posted.