Are there any good hiking trails or any districts or cool places that I should visit? This will be my first time there, so everything will be new to me!
Take a day trip to Guatape. While there, swim in the lake, and climb El Peñon de Guatape - the rock of Guatape. Engineering and architecture buffs take note of the "zipper" construction of the stairwell… the water you drink at the top is delivered by a little old man who goes up and down that rock 20-40 times a day with supplies.
Rent a bike and hit the hills above Medellin in the Edificio Hills for a morning of breath taking high altitude road biking. Road cycling is the second most popular sport in Medellin after football (soccer) and you will see why with the views from 10,000 feet. Bring a spare pare of lungs.
Ride with some locals in a Chiva (Party Bus). Originally designed to bring workers into and out of the city, these decorated buses rapidly became a party in their own right and a part of Colombian culture, they frequently include live mariachis. You can organize through your hotel, but make sure you jump on one full of Colombians, not tourists, and expect to make a LOT of new friends.
In Situ (Jardin Botanico, also do amazing non-casual dinners), you can order a picnic complete with wine to eat right there in the garden.
If you like watching sports, go to game at El Estadio (The Stadium) Estadio Atanasio Girardot Medellin while local hot-shot club Atletico Nacional is playing. The energy will blow you away - make sure you buy the team shirt or wear green, Colombians take their football very seriously.
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