Heading to Uspallata VIa Villavicencio

Although it takes a couple hours longer than heading straight north on RN 7, driving the RN 52 takes you to the natural springs of Villavicencio, the source of Argentina's well-known mineral water. If you've ordered bottled water in Argentina, chances are it's Villavicencio. Leaving Mendoza to the north through Las Heras, you'll be driving on the old international road to Chile. After 34km (21 miles), you'll pass the Monumento Canota, the spot where generals San Martín and Las Heras split to confront the Spanish at different fronts in 1817. After Canota, you will begin to climb the Villavicencio Valley, and by 40km (25 miles), the road turns to gravel and becomes winding (the road here is known locally as the Caracoles de Villavicencio, or "the snails of Villavicencio"). A small ranger station at 50km (31 miles) offers information on the Villavicencio natural reserve, including sources of the mineral water and the region's flora and fauna. Eagles, condors, pumas, mountain cats, foxes, ostriches, guanacos, flowering cacti, and many plants and trees occupy the area.

Villavicencio

45km (28 miles) N of Mendoza

French-owned Danone purchased the rights to this land and its mineral water, and it is working hard to preserve the integrity of the springs. This explains why the Hotel Termas Villavicencio, frequented by Argentina's high society until its closing in 1980, has not reopened. The lush gardens of the Normandy-style hotel, seen on the label of Villavicencio bottles on tables up and down the country, are off-limits. Perched against the dusty foothills with oaks and poplars, trickling streams, and wildflowers surrounding it, the hotel's location represents a lush little paradise in the Andes. A small chapel, opened in 1941, lies just behind it. Next to the hotel, you can stop at the Hostería Villavicencio for lunch or a drink.

The Uspallata Valley

Continuing along RN 52, you will follow the path that San Martín used for his liberation campaign. The dirt road zigzags its way up the canyon, dotted with silver mines exploited by the Spaniards in the 18th century. When you get 74km (46 miles) from Mendoza, you will have climbed to the 3,000m (9,840-ft.) summit. From here, you'll have a magnificent view of Aconcagua and the mountains, and the road begins to improve.

The road from the summit to Uspallata is a breathtaking 28km (17-mile) drive through the Uspallata Valley. You will descend into the valley through a small canyon, and when the valley emerges, you'll be treated to one of the most beautiful sights in Argentina. The polychromatic mountains splash light off Aconcagua to your left and the "Tiger Chain" ahead, with occasional clouds painting shadows on some mountains and allowing sun to pour light on others. The curious rock formations surrounding you were filmed for the dramatic setting of Seven Years in Tibet, starring Brad Pitt. Just before you arrive in Uspallata, 2km (1 1/4 miles) north of town, you will see Las Bovedas -- peculiar egg-shaped mud domes built in the 18th century to process gold and silver for the Spaniards.

Heading to Uspallata Via Potrerillos

This drive is significantly easier than the route through Villavicencio, taking you along the RN 7 through the Precordillera mountains. Follow the signs from downtown Mendoza that point to the REPUBLICA DE CHILE. Potrerillos is a bit of a ghost town along the Río Mendoza, where tour companies arrange white-water rafting, horseback riding, and trekking. There is a gas station here. Argentina Rafting Expediciones has its adventure park off the RN 7. It's a great recharger. There is also a small restaurant. A few kilometers upriver, the new Pueblo del Río Mountain Resort (tel. 261/424-6745; www.pueblodelrio.com.ar) has rustic cabins built with stone and wood that sleep up to eight people each. They have fully equipped kitchens and outdoor grills, and costs $90 (£61) for two people. There's also a good restaurant. This is a great place to clear your head after trolling around the wineries, and the Aires de Montaña Spa, part of the resort, offers all the classic treatments to rejuvenate you. It is the nicest place to stay en route to Aconcagua. The drive continues 41km (25 miles) alongside the Mendoza River to Uspallata.

Uspallata

58km (36 miles) N of Mendoza

With only 3,500 inhabitants (many of them members of the military), Uspallata is a pretty sleepy place. But this small Andean town surrounded by lovely poplar trees and the biggest mountains in the Americas offers a variety of outdoor activities and makes an excellent base from which to explore the mountains. You can obtain limited visitor information from the tourist information booth, open daily from 9:30am to 8:30pm, at the corner of RN 7 and RN 52. Gustavo Pizarro is the area's best tour guide, and his Pizarro Expediciones, RN 7 (tel. 2624/420003; www.pizarroexpediciones.com.ar), organizes horseback riding, mountain biking, climbing, and white-water rafting tours. If you need gas or any supplies, get them in Uspallata, which is the last real town before the Chilean border.

Heading to Aconcagua

Continuing along the RN 7, you'll drive through the wide U-shaped valley carved from ancient glaciers and loaded with minerals such as iron, sulfur, talc, and copper. As you climb the canyon, you will see on your left the first signs of the atrophying Andes railway -- an old, narrow track from 1902 that lifted an early-20th-century steam train up the mountains. The railroad was abandoned in 1980, due to a political dispute between Chile and Argentina, but it received new vigor in 2006, when presidents Kirchner, of Argentina, and Bachelet, of Chile, agreed to start it running again. The $436-million project -- necessitated by increased Argentine exportation and increased Chilean demand for imports -- should be finished by 2010. The goal is to build a weatherproof line that won't be snowed out, as are hundreds of cargo trucks on this road each winter. No word yet if they will also implement a tourist service, for this is bound to be one of the world's most beautiful train tours.

When you get 20km (12 miles) from Uspallata, you'll come to Puente Pichueta, a stone bridge over the Pichueta River commissioned by Fernando VII in 1770 to allow messengers to cross from Argentina to Chile. The road leading to the bridge forms part of the old Inca trail. The lone tree beside the bridge is a nice picnic spot.

A Shared Backbone: Crossing into Chile -- Trans-Andean neighbors, sometime rivals, colleagues, and "cousins," Chile and Argentina are intricately linked as nations. They share a 5,150km-long (3,193-mile) border from the high deserts of the north to the wilderness of Tierra del Fuego. The busiest border crossing is here at the Paso de Los Libertadores; these border posts are open 24 hours a day for most of the year. In winter, from May 15 to September 1, it's open from 8am to 8pm, or only when the road is open. From here, it's a steep and scenic 3-hour descent to the Chilean capital of Santiago.

Los Penitentes

165km (102 miles) W of Mendoza

Los Penitentes is a small resort for downhill and cross-country skiing. Twenty-three slopes accommodate skiers of all levels, and a ski school instructs novices. Skiing is pricier but much better in Portillo, Chile , but if you decide to stay in Los Penitentes, consider lodging at Ayelan, RN 7, Km 165 (tel. 261/427-1123), across the street from the ski resort, with basic rooms looking toward the mountains. Doubles cost roughly $75 (£51), including breakfast, and the rustic dining room serves a limited selection of high-quality regional dishes. If you are in Mendoza in winter and like to ski, this makes a good day trip.

Note: Serious skiers with more time to ski or snowboard should make the trip to Portillo (www.skiportillo.com), a much larger and better-equipped resort across the Chilean border. Better yet, head south of Mendoza to Las Leñas.

Puente del Inca

6km (3 3/4 miles) W of Los Penitentes

Although it's become somewhat of a tacky tourist trap, the remarkable bridge Puente del Inca is nonetheless beautiful. First described in 1646 by the Spanish conquistadores, it's a natural stone bridge used by the Incas to cross the Río de las Cuevas, about 6km (3 3/4 miles) past Los Penitentes. With its beautiful display of natural colors, it is believed to have once been a bridge made of ice that was hardened by the thermal springs. Now it's holding a fragile balance between natural cementation and erosion. So it's off-limits to visitors -- you can look at it, but you can't walk on it. Under the bridge, you will see the remains of an old spa that once belonged to a hotel, built in 1917 to capitalize on the thermal springs. That hotel was destroyed in an avalanche in 1965, but, in what many consider a miracle, the adjacent church went unscathed. Natural hot springs still flow underground here, but access is closed to the public. Near the spa, vendors sell handicrafts. Hostería Puente del Inca (tel. 261/429-9953) is the best place to eat here. It's a bit stuffy and seems to be trapped in the 1950s, but the set menu is reliable and well priced at $12 (£8.20).

Parque Provincial Aconcagua

Just after Puente del Inca, you will come to the entrance of Aconcagua Provincial Park. At 6,960m (22,829 ft.), Cerro Aconcagua is the "Roof of the Americas" -- the highest peak not just in South America, but also in the entire Western Hemisphere. From RN 7, you can see the summit on clear days. For a great look at it, get out of the car at the parking lot on the north side of the highway and hike the 15 minutes to Laguna Los Horcones (there is another stellar view from Km 34 on the road btw. Uspallata and Villavicencio). First climbed in 1897, it is a challenging, although not overly technical, climb, where your body battles the stresses of high altitude in an extreme environment. Only highly experienced climbers should even think about this as a goal -- it requires fitness, strength, and endurance, as well as a certified local guide. Most people take over 2 weeks to climb, giving themselves at least 1 week to acclimatize to the altitude before pushing for the top. The south face, which gets little sun, is the most treacherous climb. The normal route is along the west side. The main climbing season is in January and February, when dozens of expeditions from around the world converge to tackle one of the prized Seven Summits. The rest of the year, the park is virtually deserted.

The provincial park includes 71,000 hectares (175,441 acres) of stunning high-mountain country tucked on the eastern side of the border between Chile and Argentina. To enter the park, however, you must first obtain a permit from the park's "attention center," called Edificio Cuba (tel. 261/425-2031; www.aconcagua.mendoza.gov.ar), inside Mendoza's Parque San Martín. The location where you can buy permits changes periodically, so check with Mendoza's tourism office for additional details. Permits for 2, 7, and 20 days are available. With one of the shorter-duration permits, you can hike to the base camps without climbing to the summit. Those hoping to reach the top must buy a 20-day permit, which costs $500 (£339; including emergency medical insurance) in high season. The top guiding company in the park is Fernando Grajales Expediciones (tel. 800/516-6962 or 261/15-500-7718 [cell]; www.grajales.net), which offers 3-day hikes as well as 19-day summit attempts. Another recommended outfitter is Aconcagua Trek (tel. 261/431-2000; www.rudyparra.com). Also try Aymara Adventures & Expeditions (tel. 261/420-2064; www.aymara.com.ar), which has horseback-riding trips in the provincial park.

After visiting the park, if you have time to go a bit farther and still make it back to Mendoza before too late, continue on to the official border point. At 4,000m (13,120 ft.) above sea level, it's a wild and woolly place. The famous towering bronze monument Cristo Redentor was erected by the neighboring nations in 1902 after they resolved a territorial dispute. Then return to Mendoza via Potrerillos on the RN 7.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.