Shanghai is on the clock:

"349 days 12 hours 5 minutes 3 seconds."

The Chinese city is counting down the rotations of the Earth to the start of Expo 2010, the world's fair expected to draw 70 million visitors over six months.

Beijing, take a seat; now it's your sister's turn. "349 days 12 hours 4 minutes 52 seconds."

In the city of 18.8 million people, oversize clocks loom on plaza squares and inside public buildings. Many visitors, especially Chinese, stand beneath them, straightening their spines and grinning for the camera as Shanghai gets a few ticks closer to opening day.

Expo clock-watching would be a sport here if Shanghai knew how to kill time. But the city, an economic renegade in the communist country, is dialed to high speed, trying to be the first to reach some undefined finish line. Drivers disregard speed limits and red lights; pedestrians move with the force of an undertow; futuristic-looking buildings materialize nearly overnight. Even the steamed dumplings are ready before you've had a chance to unfold your napkin.

While Shanghai fixated on the next horizon, I wanted to take a few steps back, to return to the past before catapulting toward the city's future. But first, I had to drag myself away from that clock.

For a crash course in Shanghai's chronology, find a spot on the Bund, the scenic quay along the Huangpu River, and spin 360 degrees. In that whirl, you will see tourists eating cotton candy; 19th-century neoclassic buildings once lorded over by Western bankers; and, across the water, the Jetsonian skyline of the Pudong district. In that wide-angle gaze, you witness the old, the new and the now.

CENTURIES BLUR

"It's an ancient city and a modern city," said Zhu Tao, a student I met at the City God Temple, a Taoist shrine that was built almost 600 years ago and has been destroyed, reconstructed and repurposed many times since. "Now, it's an international city and the heart of Chinese economics."

The former fishing village near the mouth of the Yangtze River was significantly shaped by Western influences, a consequence of the 1842 Treaty of Nanjing, which opened the port to foreign trade. Europeans and Americans streamed in, unpacking their tastes from home, such as horse racing, cabarets and red meat. They staked out settlements (the Brits and Americans in the International Settlement, the French in the French Concession), leaving the Shanghainese with a small patch of land now called Nanshi, or Old Town.

But the rise of the global market — hundreds of Fortune 500 and multinational companies have a Shanghai address — has blurred the borders and fuzzied the characters of these neighborhoods. On a map, the areas appear clearly defined; on foot, I never knew whether I was in the French Concession, the International Settlement or Old Town. I frequently ended up lost and searching wildly for my landmarks — the Bund, Renmin Square (the Central Park of Shanghai) and the river.

Sleeping with history isn't as musty as it sounds. The Astor House Hotel was the city's first Western-style accommodations, built during the Qing Dynasty (1846, using a Western calendar). Famous overnight guests included Charlie Chaplin and Albert Einstein, and for a few extra yuan, you can request the same room those greats stayed in.

En route to East Nanjing Road, a busy commercial thoroughfare dating from 1851, I walked along the Bund and through the International Settlement, passing stately banks and trading houses. The mile-long strip is an architectural buffet of such styles as art deco, romanesque, gothic and beaux-arts.

East Nanjing is one of the busiest shopping streets in the world, and that was true even back in the horse and buggy days.

Gaudy emporiums, higher-quality boutiques and sprawling department stores flow into one another. I could buy a hand-sewn silk jacket the color of a rose petal for $160, then go two storefronts over for a pair of beaded "silk" flats for $9, bargained down from $21. This is also the marketplace for knockoffs.

SHOP, SHOP, SHOP

Unlike brash East Nanjing, Old Town revealed itself with a whisper. The tight back lanes, which barely fit two bikers riding side by side, are lined with laundry draped from lampposts, wires and cornices, ghostly figures dancing in the breeze. Four men played mah-jongg under a dangling pair of sweat pants. Patrons eat bowls of steaming noodles at plastic tables pushed against the wall of the City God Temple. If necessary, they could use the sock overhead as a napkin.

With little warning, the residential quadrant spat me out into a massive shopping complex. Before 1949, this area was a Chinese settlement encircled by a wall built to rebuff Japanese intruders. Now, East meets West meets Visa. One of the main attractions here is the Yuyuan Bazaar, a crazy labyrinth of shops fashioned after Qing and Ming architectural styles. Abutting the outdoor mall is Yuyuan Garden, a five-acre sanctuary built by a government official for his parents in 1577.

At a street corner near the walled entryway of the garden, I was approached by a gentle man with a smooth, round face, crooked teeth and button eyes. He asked if I needed help but knew exactly what I required: directions and a cup of tea.

As Chen Shen Sheng guided me to his tea shop, weaving through throngs of shoppers, I asked him about Shanghai's past. As we passed beneath the winged tip of a faux-pagoda rooftop, he looked at me with amusement and regret and said, "If you want to see 2,000 years of history, you go to Xi'an. If you want 500 years of history, go to Beijing. If you want to know what will happen, you go to Shanghai."

SCRAPING THE SKY

Shanghai shows its economic might with skyscrapers and a brocade of neon that outshines the constellations. The air is thick with pollution, and the river is a dumping ground for untreated sewage.

The 1,614-foot-tall Shanghai World Financial Center, which opened last year, is the second-highest structure in the world.

But the structure that most screams "ascend me" is the gaudiest edifice in Pudong, the Oriental Pearl TV Tower. The 1,535-foot-tall building features a pair of plump bulbs on a slender frame that lights up like Christmas in Vegas. I much prefer its cartoonish goofiness to the serious gray facade of the financial center.

In the observation tower, I peered beyond the bright lights into a dark and empty stretch of ground along the Huangpu River. In 349 days 11 hours 42 minutes 3 seconds, Expo 2010 will open there.