For a teenager, trekking to the Incan ruins of Machu Picchu is an incredible and once-in-a-lifetime event. Even though the Inca Trail is 26 miles long and occasionally very steep, if completed over several days as is the usual approach, it is not an impossible challenge. Arrange a four-day, three-night (or longer) trip with a reputable outfitter, and prepare for breathtaking scenery. Topping the bonding experience of seeing the sunrise over the ruins, which are situated about 8,000 feet above sea level, will be difficult.