Calingasta Valley

The most beautiful part of the province, this long fertile valley lies 100 km west of San Juan between the jagged peaks of the snow-capped Andes

and the stark crinkled range of the Sierra del Tontal, west of San Juan city. Inhabited since at least 10,000 BC, the Calingasta Valley was once the route of the Camino del Inca and though little of this history remains today, it still carries a compelling attraction. Its few oasis villages are charming places to stay to explore the hills, utterly tranquil and unspoilt.

The road from Pachaco to Calingasta follows the winding course of the Río San Juan, through a steep sided gorge of astonishingly coloured and stratified rock. After Pachaco, the landscape opens out, and Calingasta village lies at the confluence of the Ríos de los Patos and Calingasta, a vivid green splash on the otherwise arid landscape. This idyllic, secluded little village (1430 m, 135 km west of San Juan) is a delightful place to rest for a few days or plan a trek into the mountains. The Jesuit chapel,

, is worth seeing, a simple adobe building dating from the 1600s, with the ancient original bells. There is a

Another peaceful oasis, Barreal (1650 m) offers more accommodation and services than Calingasta, and is the best base if you plan to trek into the Andes. However, it's still small and quiet enough to feel like a village, and offers spectacular views of the peaks all around. From here you can explore the mountains

of

, which rise to 4000 m and give superb views over San Juan, Mercedario and Aconcagua, or climb the mighty

(6770 m) itself, one of the Andes' greatest peaks.

is famous for

(wind-car racing), thanks to its vast expanse of flat land known as Barreal del Leoncito, parallel to the main road, south of town.

Another, more tranquil attraction, are the two observatories at nearby

(2348 m)

The observatories

were

built here because the climate is so sunny, with 320 clear nights a year, making it a perfect place for observing the stars and planets. The observatories are set within an immense nature reserve, covering 76,000 ha of the western slopes of the Sierra del Tontal and rising to over 4000 m. To the west there are fine views of Mercedario and other peaks in the

with the flat plain and lush valley between. But hiking in the reserve is limited to one short walk to a small waterfall, near the entrance. Fauna includes

(rheas), guanacos, red and grey foxes and peregrine falcons. There's no public transport except

taxis from Barreal; take the partly paved road (17 km) that turns off the Route 412, 22 km south of Barreal. The

, elleoncito@apn.gov.ar

, is in Barreal. There's also a ranger post at the observatory entrance; but no facilities, so if you if you want to camp, take all supplies.

Known in Chile as El Ligua and rising to 6770 m, the mighty peak of Mercedario, south- west

of Calingasta, is considered by many mountaineers to be a more interesting climb than Aconcagua. It was first climbed in 1934 by a Polish expedition which went on to climb the nearby peaks of Pico Polaco (6050 m), La Mesa (6200 m), Alma Negra (6120 m) and Ramada (6410 m). This is a serious climb, and requires the same time to adjust to the altitude and the careful preparation as Aconcagua. You must not consider this expedition without hiring an experienced mountain guide (

), who can provide mules if necessary, as there are no facilities and no rescue service. The best time to climb is from mid-December to the end of February. No authorization is required to climb but it is advisable to inform the

at Barreal. Note that the mountain passes to Chile here are not officially open, making the crossing illegal.

San Agustín is a rather charming little town, 250 km northeast of San Juan, and is definitely the best base for exploring the Ischigualasto park, with several good places to stay and eat. You could also fish in the Dique San Agustín, and buy ponchos and blankets from the local weavers here. There's a very helpful

,who can give you a map and advise on accommodation.