White clouds of steam roll from under the light, porous lava rocks inside the crater. Occasionally a small lizard scampers across the rocks, and scrubby tufts of grass sprout here and there. But those are the only signs of life at the summit of Mount Vesuvius. There is no sound. No fire. No smell.

Yet this is the volcano that on Aug. 24, 79 A.D., breathed fire and lava, devastating Pompeii and the surrounding area of southern Italy, and killing thousands. Over the centuries, there have been dozens of periods of volcanic activity, with the last eruption in 1944.

Today, Mount Vesuvius is at rest and the most telling clue to its dormant power and deadliness is that at the summit there is almost no sign of life. Peering into the crater from the 4,000-foot summit, you see layers of multicolored rock -- ranging from mustard to brownish-pink -- fading into dark, volcanic sand.

A tour of Pompeii with its monumental streets, temple and houses is a must for the visitor to Naples or the surrounding region of Campania. But it's also worth the time to take an extra day to explore the volcano that made Pompeii famous and the remains of Herculaneum (called Ercolano locally), the other town that was engulfed by the same eruption.

The first time I saw Mount Vesuvius, I didn't recognize it. A tumultuous midday, rush-hour stand-up ride on the Circumvesuviana railway from Naples had deposited a friend and me in Sorrento. We headed from the railway station to a scenic overlook from which we could contemplate Sorrento Bay while lunching.

Through the blue-gray mist we could barely make out an amorphous shape rising above the sea. Without consulting a map we assumed that the shape must be the Isle of Capri.

"No, that's not Capri. That's Mount Vesuvius," explained a friendly English resident of Sorrento with whom we shared a park bench.

We soon learned that Vesuvius dominates the landscape from Naples to Sorrento. It waxes and wanes. It is black. It is reddish-brown. It is blue-gray. Because of the haze it is -- all too often -- invisible. But it dominates.

We wanted to visit the famous crater of Vesuvius, but quickly learned that it is difficult to get information about the mountain. (The tourist office in Sorrento told us there is no tourism authority responsible for Vesuvius.)

But we set out anyway, equipped with climbing shoes and warm clothes.

We rented a car and followed the A3 national highway north from Positano, where we'd spent the night, to the Ercolano exit and followed the yellow signs marked "Vesuvio" through a residential area. Suburban villas, some with elaborate gates and gardens, dot the lower green landscape of Vesuvius.

Soon we were part of a line of cars and buses carrying tourists up the mountain. At an intersection marked "observatory" virtually all the traffic turned right -- toward the chairlift station -- but we continued into a weird moonscape scarred by the pockmarked gray lava deposited during the volcano's 1944 eruption.

The road suddenly ended at a souvenir stand, where we bought tickets entitling us to climb up to the crater.

Our shoes sent riffles of reddish-brown granular dust down the mountain as we alternately climbed and turned to catch views of the calm sea and suburban towns below.

After about 30 minutes of climbing, we saw another souvenir stand, a snack bar and the cables of the chairlift at the summit. (The chairlift was not operating that day, and the guard could not tell us when it would reopen.)

From about 11 a.m. to noon, we had the crater virtually to ourselves. Only a few other hikers appeared. We strolled leisurely around the edge, peering into the center and watching the play of light on the rock formations. Gingerly placing our feet in the loose sand, we descended a few hundred yards -- as far as the guards would allow -- on a trail into the crater to investigate the steam seeping out of the rocks.

Finally we left this hypnotic and eerie landscape for the second part of our journey into antiquity -- to the town of Herculaneum at the base of Vesuvius.

At the same time Vesuvius' lava covered Pompeii to the south, it also oozed down the west side of the volcano to the coast of the Tyrrhenian Sea and into the suburban villas of the resort town of Herculaneum. This town of 5,000 was a coastal retreat for well-to-do Romans and the home of craftspeople, fishermen and farmers.

On top of the lava came a torrential rainstorm that turned the volcanic material into a mud carapace around homes, shops, streets and religious shrines. Entombed in this protective shell until the first signs of its existence were discovered in 1709, Herculaneum today is a subtle and melancholy reminder of the power of nature.

From the entrance to Herculaneum, we followed the sloping ramp suspended over the excavation site. Just ahead was the dark, brooding volcano.

At the end of the ramp, the streets of ruins spread out in a grid, dividing the town into neighborhoods where villas still stand, some of them two stories high and many still graced by fragments of frescoes, statues and mosaics.

The objects of that long-ago daily life remain: water jugs, a charred bed, a delicate shred of cloth still hanging on a loom, beehive-shaped ovens, large black stones used for grinding wheat, rows of shelves where people left their clothes while bathing in public baths.

Although the streets form a grid, there is no perfect route for seeing the sights systematically. We zigzagged up one street and down another, and managed to see most of the important sights: the pillar-lined main street; the men's and women's Forum baths, each with rooms for cold, tepid and hot baths; the House of the Mosaic Atrium with its black-and-white-checkerboard -- but sadly sagging -- mosaic floor; the House of Carbonized Furniture, with charred bed and table; the House of Poseidon and Amphitrite, named for a mosaic that depicts the mythological figures; the House of the Stags, a sumptuous seaside retreat named after the two stag statues that still stand in one of its rooms; and the Palaestra, with its cross-shaped swimming pool and athletic fields.

In less than two hours we'd seen the main sights of Herculaneum. We were ready for Pompeii.