Cusco isn't just an impressive Spanish-colonial city in Peru's southern highlands. It's also the historic capital of the Inca empire. Today's tour begins at the indoor San Pedro Market, in the heart of the colonial center. This is as authentic a Peruvian experience as it gets, since locals come here daily in droves to stock up on fresh produce. Be sure to try their endless selection of fresh fruit smoothies, which are the perfect refreshing treat.

After the market is a visit to the most important religious site of the Inca Empire, the Sun Temple, known as Qoricancha. This temple is not only intact but incredibly well preserved. Within it, there are even smaller temples dedicated to the moon, rainbow, stars, lightning, and thunder, among others. From Qoricancha, it's a short walk to another religious site called Sacsayhuaman, an Incan citadel and defensive fortress that was constructed in the 13th century out of giant stone blocks. The engineering and stonework of the structure was so impeccable that you can't slide so much as a sheet of paper between the stones.