A view of the Douro River in Porto. Photo: Tiara Lin

China is not the only place where you can find so-called "ghost cities," cities filled with newly built houses empty of all life. Here in Porto, Portugal's second-largest city, empty houses and crumbling shops are a major part of the city.

Porto is a city with two faces. Standing at the top of the city's landmark Clerigos tower, I could see the city's most successful business just across the Douro River: port wine cellars. However, while wandering around the historic city center, the number of abandoned houses and shops left me stunned. Every street corner hinted at economic troubles.

Why were there so many empty buildings without owners and so many people without homes? These are questions visitors often find themselves asking locals.

The Portuguese financial crisis that began in 2010 has led to looming bankruptcy and rampant debt. Jobs have been cut, debt has deepened, houses have been emptied and young people have left the city. For years the city struggled to recover. It wasn't until 2014 that things started to turn around.

Now this ghost city is coming back to life in a new hip way. Just last month, Vogue magazine published a story about Porto that predicted the city will be Europe's next hot spot.

March is one of the best times to visit Porto in terms of the weather. It was snowing the morning I left Switzerland, but two hours later I was greeted by unseasonably bright sunshine and a gentle breeze.

Before coming

There are two things you need to know before visiting Porto. First things first: wear comfortable shoes. If you are looking for a trip that will provide a workout for your legs, Porto is the right place for you. It is a city that will wear down your shoes and wear out your socks. I burned at least 400 calories every day and wore out two pairs of socks just walking up and down the city's hilly landscape.

Second, leave your suitcase at home and bring a backpack instead. When I walked out from the main train station São Bento and looked up at the hills, I wanted to dump my suitcase right there and then. By the way, the São Bento train station is one of the most beautiful railway stations I've ever seen in Europe. It takes forever to leave the station because tourists are constantly stopping to admire the many mosaics on the walls.

The walk from the train station to my hotel took just 10 minutes, but it felt like a century. Walking uphill on those narrow, cobbled streets with a suitcase was such torture it was embarrassing. As I headed to the hotel I began to fear that the noise I was making was going to wake up half of old town and drive the other half crazy. I was sure that after my arrival it wouldn't be long before the city banned noisy suitcases on wheels. When I finally arrived at my hotel, I was already half dead.

The hotel where I was staying was the Poets Inn, a newly refurbished house located in the old part of town. Each room tastefully mixed contemporary decoration with retro color. It fit perfectly with the hip new image Porto was building for itself. However, I was so eager to explore the city I didn't spend much time taking it in, instead I quickly dropped my suitcase and headed out.

The worst tours

Porto has the worst walking tours in the world. Don't worry, I'm not complaining. It's just that a group of out-of-work local architects have actually organized an unlikely series of walking tours they call "the worst tours."

Different than other tours, the worst tours help tourists find the hidden history behind the city and show tourists the impact of the economic crisis. Some have criticized them for taking advantage of the city's economic downfall, similar to slum tourism. A tourism official once told AFP that such tours hurt the city's reputation at a time when Porto is badly in need of tourist dollars.

Nevertheless, I think the tours are actually a fun and alternative way to get to know the city. Tourists can book one of these worst yet free tours on the tour's website. A single tour takes about 2-3 hours. The meeting point is at a public square called Marquis of Pombal Square. I was told to not worry about getting lost, as that was actually the fun part of the tour.

A lot of questions may come to you during the walks, such as "Why are there so many empty buildings?" and "How has Porto dealt with the crisis?"

Porto, home to 240,000 people, has been losing residents over the past decade as family bankruptcy forced people to abandon their houses. According to official data reported by AFP, 18 percent of the apartments in the city were empty in 2011, comparing to 15 percent in the capital Lisbon.

Minimum wage in the city is only 500 euros ($700) a month, lower than the 750 euros in Spain and 1,300 Euros in France. To attract foreign investors, Portugal launched a "Golden Visa" program in 2012 to boost the property market in exchange for resident permits.

According to a Bloomberg report, at least 80 percent of the 2,800 golden visas have gone to Chinese.

"The Chinese came at a difficult time for Portugal, when many didn't believe that the country could face and overcome the crisis," Antonio Costa, the mayor of Lisbon and leader of Portugal's Socialist Party, was quoted as saying. That's probably explained why wherever I went, I saw warm smiling faces looking at me.

For travelers who enjoy the combination of history and urban architecture, who are excited about ghost hunting and have a taste for wine, Porto is the perfect place.

The postcard tour

After the ghost hunting tour, the next day I got up early to explore a part of the city that provides the perfect postcard views. The hotel receptionist gave me a map, on which were marked just a few popular attractions. Unlike Lisbon, Porto is a city you can tackle over the course of a weekend.

My first stop was the Clerigos Tower, designed by an Italian architect in the 1700s. Climbing up to the top through a narrow staircase you can have a breath-taking view of the entire city.

From there I walked to the Carmo Church and the Carmelitas Church. It was a bit confusing that the two churches were standing side by side. But they were hard to miss as you can see their shiny mosaic walls from far away as they bathe in the sunlight. Many people say they are better on the inside as they are beautifully decorated with gold and silver. They are definitely worth a peek because entry is free!

What was more confusing was a massive neoclassical style building next to the twin churches. It looked like a palace from outside, but upon entering I noticed something was wrong. I saw a woman crying at the gate and a lot of people waiting in the hall impatiently and then noticed everyone was looking at me.

"That's weird," I said to myself. As it turned out, it was not a palace, but a hospital!

Built by an English architect John Carr 200 years ago, the Hospital de Santo Antonio is still up and running. It was the first time that I realized maybe going to a hospital might not be all that bad.

After visiting the hospital, I got lost. "Enjoy it when you get lost," a local told me when I asked him for directions. I didn't know if I should thank him or hate him. While wandering around, I accidently found myself down by the Douro River and once again surrounded by people, cafes and restaurants.

In front of me was the double-decker Dom Luis Bridge. The massive iron bridge spans the Douro River and links the port wine house with the downtown Ribeira district.  So how does one cross the bridge? The lazy option is to take the cable car, but I chose to hike all my way up through the steep alleyways. It was good to feel my calf muscles burning.

On my way down, I visited the church of Saint Francis. It was a surprisingly beautiful example of Gothic architecture. If you go down the stairs inside, you can see the bones and graves of the poor in the cellar. It was kind of spooky, but the amount of gold work made the ticket worth it.

The hip tour

Why is Porto Europe's next hot spot? Vogue explained that it's because the city has good taste when it comes to contemporary innovation and possesses a serious foodie scene.

To have a taste of Porto's creative design, stop at A Vida Portuguesa. It is not an average gift shop, but a collection of beautiful treasures and creative designs. It sells everything from toys to jewelry and candy to stationery. Everything was a bit pricey, but I was more than willing to give them all my money.

The over 100-year-old neo-gothic Lello Bookshop is another must-see hip place to visit. The Lonely Planet calls it one of the most beautiful libraries in the world. When you walk through the door, you will see a marvelous red stairway connecting two floors. No photos were allowed though. According to reports that J.K. Rowling frequented here while she was living in Porto and working as an English teacher. It was this very book store that inspired her to write Harry Potter.

When you get tired of walking, stop at the Santiago Café and order Porto's most famous sandwich: francesinha, a Portuguese-style sandwich with lots of ham, sausage, roast meat and cheese. For Asian people, it might not be that great after a few bites, so you might want to share with your friends. 

When the sun goes down, you can go back to the riverside, order a glass of Port wine and enjoy watching the sunset to finish a day.