The rock paintings in the middle of the Sahara sounded unusual. I wanted to go see them, but it's a good thing I planned ahead. It took four months to organize a vacation to the Tassili N'Ajjer (The Plateau of Rivers), in Southern Algeria.

The tour included three days in the sprawling capital city of Algiers along the Mediterranean. Algeria isn't an especially easy place for an American to be a tourist. It's a totally French-speaking country, and it's expensive. Outside Algiers, there are not many restaurants. Among the few hotels for tourists in the city are the Hotel D'Jazair, a restored Turkish palace, and the Hotel Suisse, where you can't count on having running water 24 hours a day.On the day we left the city to see the rock paintings, we needed to be at the airport at 5 a.m. The two-hour, 1,000-mile flight from Algiers south to Djanet, lands at a military airport, 30 kilometers from the Arab village of Djanet.

The village is nestled in a narrow valley between the Tassili Plateau and the lava hills, at the edge of the desert. The streets in Djanet are lined with tall, thin, dark-skinned men, dressed in long, loose robes, called gondurahs, and turbans in either white, black, or drab green, called sheshes. Late in the day, when the temperature drops, a few veiled women appear.

The hub of activity is the Hotel Zeribas, which consists of 40 grass huts, each with two sagging beds, a lopsided table, and a dangling bare light bulb. An oversized skeleton key opens your own door, as well as any of the others. Meals are served in a warehouselike building. There's also a shaded patio bar, where music blares. A night at the Hotel Zeribas costs $30, including meals.

Two different trips to the paintings can be arranged through the local tour agency, called Tim Beur.

One is a day tour to Jabbaren, which means "the Giants," because the paintings found there are of giant, round-headed monsters with massive legs and tattooed bodies. Some figures carry basket-shaped vessels on their heads. Others look like men from outer space.

The other offering is a five-day guided tour, with burros carrying all gear. It's necessary to hire a guide for either tour, as it's impossible to find your own way to the paintings or back.

On the drive to the trailhead, you'll pass long, strange shadow figures on the golden sand, as the sun rises behind cross-hatched rocky spires typical of the extra-terrestrial look of the Tassili. After a short, steep climb on foot up a gorge choked with house-sized rocks, you arrive on the Tassili Plateau. Your guide will show you about 20 panels of rock art each day, which are actually not many, when you realize that there are over 5,000 panels in the Jabbaren area alone, all dating back to 4000 B.C.

The experience of staying overnight in the Tassili and sleeping under the stars on hard sand will stay with you a lifetime. The quiet is almost deafening. There's not even the intrusion of an airplane, as in the southwestern deserts of the United States. No crickets sound; no frogs croak.

It's hard to comprehend the ochre paintings on the sandstone walls and under rock overhangs. They depict graceful, running warriors carrying bows and arrows, or campfire scenes.

Along with arrowheads, knives, and scrapers, the paintings are all that remain of an unknown civilization. They are proof that what we know as the barren Sahara was once a savannah inhabited by a civilization supporting large herds of cattle, as well as giraffes, elephants, and hippos.

After seeing the paintings, you'll wonder how anyone ever found them, for some are hidden under overhangs lower than table height.

The mysteries of the Tassili art will continue to intrigue you long after you return home.

Booking a trip to the Sahara:

Several airlines, including Air France and Lufthansa, serve Algiers. Current APEX fares round trip from New York are $1044 plus tax through Sept. 14, or $851 if you travel between Sept. 15 and May 14. The best months for visiting the interior of Algeria are May, June, and October.

Book your Algiers-to-Djanet flight on Air Algerie before you leave the US; to do so in Algiers takes at least half a day. At this writing, the round-trip flight costs $166. There are two flights weekly, on Tuesdays and Thursdays at 6:30 a.m.

You'll also need visas for Algeria - and for France, if you change planes there. For details write to the Embassy of the Democratic and Popular Republic of 540 Algeria, 2118 Kalorama Rd. N.W., Washington, DC, 20008, and to the Consulate General of France, 540 Bush St., San Francisco, CA, 94108.