Ollantaytambo is an imposing Inca fortress and living town in the Sacred Valley. Built in the 15th century as a fortress and ceremonial center, it witnessed the last Inca victory over the Spanish conquistadors. It features massive agricultural terraces and the Temple of the Sun built from huge stones transported from the opposite mountain. The town below still preserves its original Inca grid layout, making it one of the best examples of Inca urban planning.