I PRESSED my nose against the bus window. After months of scrimping and scheduling, planning and provision-stocking, we were in Rio de Janeiro, with three months and a continent stretching before us. I was pumped up and raring to go.

As the bus took my girlfriend and me to a hostel in Ipanema, the tourist hotspot in south Rio, I was struck by the sharp change in scenery. One moment we were sailing through the vast, corrugated-iron patchwork of the favelas, and the next, turning off the freeway, we were amid deserted streets of dilapidated colonial grandeur.

I became accustomed to these stark differences as the months rolled by. For instance, in Ascuncion, Paraguay, I saw children looting a derelict warship for material to build a shelter, less than 100 metres from the presidential Palacio de los Lopez.

To describe South America as a continent of contrasts is a huge cliché. But huge clichés can be true.

SAO PAULO, BRAZIL

Despite raking in a lot of visitors, Sao Paulo is not a picturesque city. But it is Brazil’s largest city and the beating heart of its fast-growing economy.

Strolling around the pedestrianised centre, I stumbled on the Edifício Copan. Nicknamed “The Wave”, Edifício Copan is a 140-metre-high, sinuous structure designed by architect Oscar Niemeyer in 1954, celebrating Sao Paulo’s 400th anniversary. It is brutal and unapologetic.

My friend Andrew de Lamarra told me: “Since the 60s, historical buildings have been neglected in favour of this new look. It is about overthrowing the memory of our colonial past.” But around the corner we find the unassuming Pátio di Colegio, a Jesuit mission with low, white walls built in 1554 – the birthplace of Sao Paulo.

Another day, we walk from Ô de Casa, our hostel in suburban Pinheiros, to the renowned Museo de Arte de Sao Paulo (MASP), which was exhibiting the Brazilian artist Vik Muniz, who makes pictures out of junk. In one video, he worked with local men who lived in scrapheaps to recreate Correggio’s Venus and Cupid from the waste.

For local Matteu, whom I met that night at the funk club, it was a gimmick. “Vik likes to associate with these men who live in the rubbish,” he shouted in my ear, “but he doesn’t have to make his house out of it.”

Weeks later, on a coach outside Arequipa, Peru, I saw a man picking his way across a lake of white. At first I thought it was snow. Only as the coach drew closer did I see it was a lake of plastic bags.

ASCUNCION, PARAGUAY

Buses, buses and more buses. Sao Paulo to Foz d’Iguazu to Podemas to Encarnaçion to Asuncion – I was beginning to understand the sheer size of South America. It rolled on and on.

Paraguay, one of the poorest countries in South America with GDP per capita of £2,600, certainly had the worst buses – many are bought second-hand from Brazil. So I was understandably anxious as I set off on a 24-hour bus jouney across the Chaco plains, bound for Santa Cruz, Bolivia.

The aisle was crammed with people selling their wares.

Old women hauled bags of oranges aboard. Young men flashed DVDs. A salesman persuaded half the coach to buy lucky charms at half price. Unlike in Brazil, these weren’t products for tourists, these were for anybody.

At 3am, the police stopped the coach. Lights came on. A child started crying.

They told one woman to open her suitcase. They shone a torch in my girlfriend’s handbag. They knocked on the ceiling of the bus, checking for secret compartments and then were gone. Some people hadn’t even bothered to wake up.

Potosi. Uyuni. La Paz. Copacabana. Lake Titicaca. Isla del Sol. Next stop Cusco and the wondrous Machu Picchu.

Arriving in Cusco, old capital of the Inca Empire and springboard for anyone travelling to Machu Picchu was a culture shock after weeks in Paraguay and Bolivia. There were too many “I Luv Cusco” T-shirts and I was glad when we set off for Machu Picchu.

There are various trails around it. The famous Inca Trail is £300 and you must book six months ahead.

We opted to follow the Lares Trail, which offered a similar experience for £260, together with great immersion in local Quechuan culture.

A four-day, 39km hike through mountain passes up to 4,500m high is always going to be an exhilarating challenge. Among other firsts, I walked through a cloud.

One afternoon, when I felt I could not go on, a sturdy Quechuan women powered past me up the mountain.

Astonishingly, she had a baby strapped to her back, was carrying a basket piled high with vegetables and still had spare breath to shout continously at her son.

Pausing for a moment, I was bemused to see the woman’s husband strolling behind, holding only his bowler hat.

It turned out that the Lares Trail didn’t lead to Machu Picchu, but to Willoq, a Quechuan vilage in a nearby valley.

Everyone found this disappointing. I might as well have hiked my heart out in the Pennines and seen Machu Picchu on a different day. So, for anyone visiting Machu Picchu, dig deep and book early – do the Inca trail.

PERU

Emerging from the Andes after altitude sickness and freezing nights, we were going down to where the air was fat – to Pisco, home of the Pisco Sour cocktail, on the Pacific coast.

We first sensed something amiss when the bus didn’t go through Pisco. We scrambled off and took a taxi, but the driver tried to take us to neighbouring Paracas. We insisted on Pisco. He became animated. Terremoto, he said over and over and jabbed his hand at the floor of the car.

I later discovered he was talking about the earthquake that devastated the central coast of Peru in 2007. Pisco suffered badly. As we pulled in, I saw many houses were made from wicker. By contrast, the town square is surrounded by sparkling banks, pharmacies, casinos and an upmarket restaurant. While I enjoyed the food, I was left with a bitter aftertaste as I walked back to my hotel along the cracked roads.

Weeks later, in Santa Marta, Colombia – a country whose tourism industry is finally picking up after years of civil conflict – I met a mad and shoeless old salesman who shouted at any gringo who passed: “Thank you for believing in Colombia!”

One day, I hope, tourists will believe in Pisco again too, even if it means a flood of “I LuvPisco” T-shirts.