Argo Tunnel

The Argo Tunnel is a mining adit that runs through the Rocky Mountains, joining multiple gold mines with an underground drainage system. The passage stretches across several kilometers and includes reinforced sections where the tunnel intersects with major ore deposits and mine shafts.

Construction began in the 1890s and took many years as workers gradually tunneled through the mountains, discovering ore deposits along the way. This was one of the major engineering projects that shaped how gold mining developed in this area.

The tunnel represents a crucial part of how miners connected their work across mountains, showing the engineering skill needed to manage water and ore movement. Walking through it today, you can sense how miners coordinated their efforts underground to solve practical problems.

You can reach the site along Riverside Drive in Idaho Springs, where rangers guide you through the tunnel. Wear sturdy shoes since the passage is often wet and slippery from drainage water.

The tunnel was built with a precise downward slope running its entire length, allowing water to flow naturally without pumping. This engineering achievement was remarkable considering the limited surveying tools available at the time.