Medellín, Colombia, was once considered the world's most dangerous city, and was best known as a hotbed of violence during the country's civil war, as well as the base of drug lord Pablo Escobar.
The city is now considered one of the world's most innovative, with its transport systems playing an unusual role in not only symbolizing the changes in Medellín, but actually helping to bring it about by connecting people in hard-to-reach areas to new opportunities.
One of these systems is the city's network of cable cars that, like ski lifts, bring you over the rooftops of the neighborhoods that sprawl up the mountains that make up much of the city.
Medellín's first cable car line opened in 2004, and was intended to connect parts of the city that had been isolated for decades. Pablo Alvarez Correa, a tour guide from the city, described them to Business Insider as "an innovative solution to the problems of geographic and economic exclusion."
The city was just coming out of a period of being known as the most dangerous city in the world, and the cable cars are credited with helping to transform the city.
There are now four separate lines, connecting the city's neighborhoods that sprawl up its mountains, and allowing people who were once isolated to easily travel into the center of the city.
Many of the city's two million people live on its steep hills, but the center, and the city's metro, are in the valley below. Before the cable cars, people would have to take two buses to get down the mountains — meaning many did not do so, and missed opportunities for work, education, and health.
Alvarez Correa told Business Insider that the cable cars act as "a symbol of resurrection or a symbol of hope" for the city.
The city was once best known as the base of drug lord Pablo Escobar. But its narrative is changing, and it has been recognized as one of the world's most innovative cities for its rapid change and bold public projects.
The cable cars connect to areas that were once considered "no-go" neighborhoods like Santo Domingo, which was once one of the city's most dangerous.
Now everyone can ride to the top and explore, something people from the city, from elsewhere in Colombia, and from abroad can be spotted doing. This is the neighborhood of Santo Domingo, at the top of Line K.
The ride provides striking views of the city.
And easy access to the bustling neighborhoods at the top.
Buses also come to these areas, but trying get down to the rest of the city this way takes much longer. This is what people relied on before the cable cars were introduced, and Alvarez Correa, said people now "have to spend significantly less time travelling."
Taking the cable cars costs around $0.80, and you only have to pay when you enter the system. This means you could get on the metro at the south of the city, ride it until the cable car line in the north, take the cable car up and down, and take the metro back, all for one fare — as long as you don't leave a station.
You pay for a ticket at a booth, and then drop it into a slot that lets you through the turnstiles.
You can see the cable cars rising up the mountain from the metro stations.
Depending on the time of day, all of the seats can be full, or you can be the only person each carriage.
The system has clear alerts and some are even in English, like this sign asking people not to eat and drink on board.
Each line makes multiple stops, and you can sit in the carriage as it goes through the stations that you don't want to get off at. Each station is bright with lots of glass, and has maps that clearly lay out the city's transport systems.
The journey is also quick — it only takes around five minutes to ride three stops up the mountain to Santo Domingo.
Riding up the mountains, you can see art on rooftops and amenities like public sports pitches.
And the ride gets you close to the city's art.
Some of this art also shows how integral the cable cars are to the community, like this mural in Santo Domingo.
Access to the metro stations comes through walkways that allow people to cross over the Medellín River.
Alvarez Correa said the success of the cable cars can be seen by how popular they are: "When you go to the metro stations that also have the cable cars at rush hour, they are absolutely packed. They are full. I think that indicates that it works."
Since Medellín introduced its cable cars, cities like Brazil's Rio de Janeiro and Bolivia's La Paz have followed suit — although its success hasn't always been replicated.
They have even become something of a tourist attraction, and are regularly listed as a must-do in the city. Alvarez Correa said that locals don't find that bizarre because "we understand its novelty."