A mountain stage from the Almería coast to the roof of the Sierra de los Filabres. More than 4,000 metres of climbing, most of it packed into the second half, including a 30 km ascent through the middle of the stage before the closing 18 km at 5.3% to Calar Alto. The finish lies at almost 2,150 metres beside the Calar Alto observatory, one of the largest astronomical sites in continental Europe, put there for the same clear, dry air that makes the climb hard to breathe on. The gradient is steady rather than savage, so it favours the strongest engine over the sharpest acceleration.