The Filipino band was doing its best to channel the Black Eyed Peas. The lead singer’s locks were as long as Fergie’s, and her dance moves just as animated. Though she was tiny, her voice was big enough to boomerang across the Beijing nightclub. Her red-rimmed sunglasses added to her mystique. All eyes were upon her.

Well, all eyes except mine. I was more entertained by the audience. On the dance floor, a heavyset Westerner was trying to moonwalk. A man in lederhosen and two women dressed like Heidi walked in and immediately joined him. Another man wearing a sombrero was ordering shots at the bar. No one seemed to think that their attire was odd. Nor did anyone seem flummoxed by the middle-aged couple gyrating on top of a table against a pole, not even when one of the pair took a tumble.

It was Friday night at Swing, a club on Sanlitun Bar Street. And the party was certainly in full swing. Strolling through Sanlitun, one of Beijing’s most popular destinations for shopping, drinking and dancing, you wouldn’t think that you were in the capital of a country considered one of the most rigid and xenophobic in the world.

But then, this isn’t the Beijing that Mao Zedong envisioned. No longer an introverted, sober capital most defined by the Great Wall, the Forbidden City and the Ming Tombs, today’s Beijing is a booming metropolis on a building, boozing and buying binge.

A lot of it is thanks to the 2008 Olympic Games. When the city was chosen as the Olympics site in 2001, the government poured billions of dollars into construction projects and neighborhood revitalization. Many worried that the businesses and buildings would empty out once the athletes and world attention went away. But China is now the second-largest economy in the world, behind the United States, and second in the sale of luxury goods. Conspicuous consumption remains high among a certain segment of the population, despite some recent stock market turmoil. Neighborhoods continue to evolve or sprout virtually overnight. Driving around Beijing, I was amazed at the number of construction cranes everywhere.

“It’s got an energy about it,” agreed Chandler Jurinka, a Rockville native who has lived in Beijing for six years and runs, a user-generated online city guide. I struck up a conversation with him outside a Starbucks at Sanlitun North, the latest mega-shopping-and-entertainment complex to open in Beijing.

Not far from us was a “coming soon” sign advertising Alexander McQueen, Christian Louboutin, Juicy Couture and Marni stores. A wine shop called the Wine Gallery — the fruit of the vine has become more popular in Beijing in recent years — had a second floor for “members only.” Inside were rows of bottles from more than a dozen countries ranging in price from $30 to several hundred. I was tempted to sneak a peek at the members-only floor, but I knew that the salesman following me around the shop would never allow it.

“Seedy bars, that’s what this place used to be,” Chandler said. “Just in the last three years, they’ve made all this.”

All this is Sanlitun Village,a prime example of Beijing’s evolution from dowdy to dynamic. It’s made up of Sanlitun North and South, and since its construction a few years ago, it has become a playground for expats and hip, young and fashionable Chinese. The Village’s bold buildings were designed by Japanese and American architects, including Kengo Kuma, SHoP and Lot-ek, and they tower over everything else in the neighborhood. The architects arranged the colorful glass structures in a maze to evoke the feeling of the old Chinese hutongs, traditional neighborhoods made up of alleyways and courtyards that are quickly disappearing all over the city.

As I walked from Sanlitun North to Sanlitun South, I could see what Chandler meant. In between the complexes is a street that has somehow managed to escape the cranes. The buildings are dirty and gray and house a sex shop, a tattoo parlor, a video store called A Little High and takeout shops. Crates of empty beer bottles lay on the ground. Some windows displayed hookahs. A man sold yams from the basket of his bicycle. I felt as though I’d gone back in time.

But just a few minutes later, I was in Sanlitun South, with its glistening two-story Apple store. I’d returned to the future.

Once, Beijing lagged behind Shanghai in the construction of buildings, roads and public transportation. But since the Olympics, the capital has become as cosmopolitan as China’s second city, while still feeling like China in a way that Shanghai does not. On a recent two-week trip, I could see the differences between the two cities as soon as I hopped off the new high-speed train from Beijing to Shanghai. Dining at a Spanish tapas restaurant in the French Concession area, it seemed as though English was being spoken at most of the tables around me. Back in Beijing, I felt that there were as many or more locals as Westerners pretty much everywhere I went.

Perhaps nowhere was that more apparent than in the capital’s Houhai lake district, where many traditional hutongs still remain. Lots of Chinese complain that too many foreigners have opened up restaurants, bars and shops in the hutongs. But Houhai’s residents have managed to embrace modernity while holding on to parts of their past. As fascinating as I found the new, sleek Sanlitun area, I was happy to explore a part of Beijing that still retained elements of the old China.

One night, a group of us, expats and tourists, strolled through the district’s narrow cobblestone passageways, some lined with small restaurants with Chinese-only menus, where locals dined on food I didn’t recognize. Just a few blocks away, we walked past restaurants advertising American and other non-Chinese fare. Shops sold antique tea sets alongside contemporary clothing.

We visited a siheyuan, a traditional Beijing-style dwelling consisting of four structures surrounding a courtyard. In the past, these belonged to working- or middle-class Chinese families. Now, Chinese live in these homes alongside foreigners and wealthy locals.

After sipping Italian wine in the courtyard of one siheyuan, we stopped by a food stand for stinky tofu, which was a bit too stinky for my taste buds. Then we crossed the bridge over the lake to satisfy a craving for Peking Duck, passing by many restaurants with outdoor seating that overlooked the water to settle on the tucked-away Quan Ju De, which had no outdoor seating and lacked the ambiance of the other restaurants. But the duck, steamed broccoli and bok choy made up for that. Most of the diners were locals speaking Chinese. Not even the waiter spoke English.

Later that week, my friends and I found yet another neighborhood that’s transforming itself overnight. The 798 Arts District, once an industrial complex for the production of military electronics designed by East German architects in the 1950s, now boasts dozens of contemporary art galleries, coffeehouses, bookstores and boutiques selling quirky Mao T-shirts alongside motorcycle helmets.

More than 300 Chinese and foreign contemporary artists are in residence or showcased at 798. We walked along several of the tree-lined streets, popping in and out of the galleries. I particularly liked the cavernous 798 Space, which featured arches painted with Maoist slogans and an amusing painting of a man’s hairy back on one wall. There was art on the sidewalks, too. Local teenagers posed before a massive bronze statue of a grossly overweight naked man. A dirty London telephone booth, which I assumed was meant to be a work of art, stood outside one of the boutiques. Several stores hawked postcard paintings of President Obama dressed as Mao.

Here was something I hadn’t expected to find in Beijing: a sense of humor.

I was craving a salad. I’d spent a week eating delicious Hunan, Sichuan and Cantonese fare, but all I wanted for lunch this afternoon was lettuce and chicken.

I was exploring Sanlitun South, the Village complex that attracts a younger crowd, as attested by stores such as Mango, Dr. Martens, Steve Madden and the wildly popular, always crowded Apple store.

I had dozens of dining options serving cuisine from all over the world, but I went into the very American-sounding Element Fresh, which specializes in salads and sandwiches. It even offers a California Hippie sandwich made with avocado, cucumbers and tomatoes. I sat on the patio, even though it was windy, enjoying the view of the ultramodern complex. At one table, a group of foreigners was discussing a presentation in English and busily tapping away on their laptops. At another, two Chinese girls were drinking tea.

When I finished my salad of grilled vegetables and chicken, I stopped to talk to manager Andy Minoie, who’s originally from Massachusetts.

His brother co-founded the chain in Shanghai and opened a location in Sanlitun three years ago because the place was booming, he told me. Business has been brisk, with a good mix of locals and tourists. In fact, 60 percent of his clients are Chinese, Minoie estimated. “Before the Village opened, there was really nothing that people would go to,” he said.

Afterward, I stopped by the piazza for some people-watching. A fountain in the center spewed water in dramatic fashion every few minutes. Parents let their toddlers run around and splash in the water. A screen against one of the buildings beamed commercials for the Village’s businesses.

I chatted with Olga Zeldina and Galina Velichko, two Ukrainians studying in Beijing.

“It’s our second home,” Olga said of the Village. “It’s an international place. You can come here and forget you’re in China, meet with friends, go shopping, eat at international restaurants.”

“Every month, there’s something new here,” added Galina.

She was right. On my way to Sanlitun South, I stumbled upon a little courtyard, with smaller shops and even more restaurants, called Nali Patio, not technically part of the Village but tucked inside it.

Later that night, my friend Keith and I returned to Nali to check out the rooftop bar at Migas Restaurant and Lounge. The view of the city was spectacular. But it started to rain, so we escaped to a bar on the third floor called Apothecary, which Keith, who’s The Post’s Beijing correspondent, thinks has one of the most creative cocktail lists in the city. The menu was extensive, and each cocktail came with a long description. It was no surprise that a bar in Beijing would have cocktails named the Millionaire Cocktail and the Bazillionaire Cocktail. I ordered the Corpse Reviver No. 2, “named for its purported ability to bring the achingly hung­over back from the precipice of lifelessness.”

I wasn’t hung over, but I was intrigued. The concoction, made of gin, Lillet Blanc, Cointreau, lemon juice and absinthe, was light and delicious. I’d drink it any day, hung over or not.

For dinner another night, we hit the elegant new Sichuan restaurant Transit in Sanlitun North. A few friends had told me not to expect to eat well in Beijing. I suspect they’d been to Beijing a decade ago, before the city’s culinary scene exploded with new restaurants and world-class chefs. Transit’s modern Sichuan menu included a spicy prawn dish with chocolate sauce, which worked surprisingly well. The service was impeccable, and I loved the soothing decor with its plush banquettes, gray-cushioned chairs and bonsai trees.

Just as swanky was the nearby boutique hotel called the Opposite House, which attracts the hip and even the famous: One Thursday night, we spotted Chelsea Clinton there. The hotel also boasts a nightclub, high-end restaurants and a revolving art installation.

When you enter the 99-room Opposite House, you can’t help looking up. That’s because of a dramatic six-story atrium with curtains of steel mesh hanging from the ceiling. The lighting is dark and moody, somehow making the whole place seem intimate.

“Have you ever seen anything like it?” I overheard a visitor with a British accent asking his wife.

He could have been asking about all of Sanlitun. And my answer would have been no.