An hour from Cusco brings you to a steep-sided valley with a wide floor that follows the course of the Rio Urubamba. This magnificent mountain river arrives into the valley close to the village of Pisac, tumbles past the 30km of fertile pastures and fields it has created, then flows out of the end of the valley at Ollyantaytambo. From that point it tumbles through narrow gorges, passes beneath Machu Picchu, and eventually finds its way out of the Andes to join the Amazon.
For the Incas, the Sacred Valley was heaven on earth. You can easily see why.
You could stay a long while in the Sacred Valley. Taking long country walks along the valley, or striding out on the highlands above. Shopping in village markets. Exploring the ruins of Incan temples and palaces. Eating hearty food. Enjoying the clean air. It's the kind of place you might feel you could settle down in sometime.
There's lots to see. Perched on a ridge above the market town of Pisac at the head of the valley, is an Incan citadel that once controlled a strategic route from Cusco to the Amazon. The views from here are astounding, looking down on the patchwork of fields and intricate terracing of the valley itself, as all around steepling peaks cascade into the distance.
Parts of the ruins at Pisac are extremely fine, with a Temple of the Sun that is reckoned to be the equal of anything at Machu Picchu. More ruins, largely unexcavated, lie above, along with ancient burial sites hidden in rocky cliffs.
The other end of the Sacred Valley was guarded by the magnificent temple-fortress above Ollyantaytambo. The ruins include a temple of the sun in astoundingly precise Incan stonework, with 6 pink monoliths to catch the rising sun.
Ollyantaytambo is itself an Incan town, laid out in the pattern of a maize cob, each grain an individual courtyard. Agricultural terracing around the village makes the shape of a mother llama with her calf.
A further example of Incan agricultural technology lies on the highlands above the Sacred Valley: the curious 'laboratory' at Moray. Here a deep circular depression ringed with terraces was created in Incan times, which archaeologists interpret as a place to experiment with crops in different conditions.
You'll also want to see the dramatic salt-pans at Salinas above Maras, and perhaps explore the town of Urubamba, which makes a good place to stay if you are spending time in the valley.
There's a train line that runs from Cusco, through the Sacred Valley to halt at Ollantaytambo and again a few kilometres on. Alight here for the start of the Inca Trail, or stay aboard for the exciting ride through deep gorges beside the Rio Urubamba, to emerge below Machu Picchu itself.