The state's second-tallest peak, Mt Massive (14,421ft) lives up to its name: it has four summits and a 3-mile-long ridge, giving it more total area above 14,000ft than any other peak in the state. From Hwy 24, it dominates the western horizon.
The classic route up the east slope is a real bruiser: you'll put in a grueling 13.6 miles of hiking round-trip. The southwest slope is much shorter at 8 miles, but you'll need 4WD and high clearance to reach the trailhead. Both trailheads are accessed via Rte 300, south of Leadville. The Tour de Massive is for those who enjoy punishment – it takes in all four summits, with nearly 15 miles (11 hours) of hiking. Start before dawn.