The route to Imogene Pass also showed us the road not taken. In the lower elevations, we spotted a massive zigzag scar rising up the vertical wall of a nearby mountain, looking like a pictograph left by a race of aboriginal giants. Impossibly, it is actually a jeep road descending from Black Bear Pass. Lest you be tempted, (1) think again, and (2) check your rental agreement, which probably prohibits you from taking that road, which my guidebook calls "one of the most dangerous passes in the state and perhaps in the country."

On our last day, we took the Alpine Loop from Ouray east to Lake City - 30 miles apart on the map, but 69 miles on jeep paths and surfaced roads. Leaving the Million Dollar Highway three miles south of Ouray, we immediately started the ascent to Red Mountain Pass. We passed the remains of long-abandoned mining camps, their mills clearly visible on steep hillsides, and the ruins of Rose's Cabin, once a stagecoach stop and later a small community with a 22-room hotel, of which only the stone fireplace remains. The most unlikely place on the loop is Capitol City, a testament to the folly of mine owner George Lee, who believed that this remote location would become the seat of Colorado's government (its population never exceeded 800). Not all of the route was so arduous: After Henson Creek, we didn't need four-wheel drive until the climb over Cinnamon Pass on the way back from Lake City.

These jeep routes are only a starting point for exploring the San Juans. Along the way, lesser-traveled side roads take you even farther off the beaten track. But you have to know what you're doing. On the Alpine Loop, for example, the side road to Picayne Gulch across Treasure Mountain is considered easy. But woe to the inexperienced driver who attempts the Poughkeepsie Gulch road, which leaves the loop around two miles west of the summit of Engineer Pass. My guidebook says that it requires "modified equipment," and if you don't know what that means, you don't belong on Poughkeepsie Gulch.