Alto de Letras is a high mountain pass at an elevation of 3.679m (12,070ft) above the sea level, located in central Colombia. It’s said to be the longest road climb in the world. It’s one of the hardest and most epic climbs you can ride on two wheels.
The road to the summit is called Ruta Nacional 50 and links Manizales and Mariquita cities. The road to the summit is asphalted and considered to be among the most challenging climbs in the world. Most people feel altitude sickness at around 2,500-2,800 meters. Starting from Mariquita, the ascent is 78.9 km long. Over this distance, the elevation gain is 3.220 meters. The average percentage is 4 %. The climb starts at a sub-tropical 468 meters, in the town of Mariquita, and tops out at an arctic 3.679 meters.