In northern Chile there lies a vast expanse of desert known as the Atacama desert. The Atacama is often referred to the driest (non-polar) place on earth. Most people visit this desert either prior to or after a trip to the Salar de Uyuni salt flat in Bolivia. I ended up in this weather starved locale after spending 3 days in the salt flats.
A couple popular towns in the Atacama are Calama and San Pedro de Atacama. I visited San Pedro as it was the destination where the salt flats tour ended. There are many excursions available from San Pedro to various destinations in the desert including geysers and volcanic mountains. One of the most interesting places in the Atacama is Valle de la Luna (Valley of the Moon).
This wind and water swept place is comprised of rock and sand formations that look representative of that which you might find on the moon hence the name of the valley. From San Pedro you can rent a bike for a few thousand Pesos for the day and bike the 13km from town out to the valley at your own leisure or you can book one of the many evening tours from the town that last a few hours and cost about 14000 Chilean Pesos (~$20 USD).
The tour begins with a hike through some cave formations which leads to an area with many stalagmites and odd rock formations which are covered in a thin layer of salt. We then headed to the top of one of the large sand dunes where you get an impressive view over the valley as well as some of the surrounding mountains all while being recited tales from Chilean history and what some of the mountains and formations represent in the Chilean culture.
The tour leaves town about 3:30pm and lasts a few hours until sunset so you can spend sunset out in the valley for an amazing view of the sun going down over the Atacama desert. The color from the sand and the various other rocks and formations makes for an unforgettable sunset.