The rainbow mountains are single handedly the second most important tour to take after Machu Picchu when in Cusco. Despite some negative press of the colours being deceptively bland, if you go on a clear day then this misconception will be debunked. Most tour agencies will touch-up and enhance their photos, so just keep in mind that it is not quite as vibrant as a literal rainbow. The hike is easy to do and takes just 2 hours to the top which is around 5000m. Prepare for bad weather as a sudden downpour may occur at any time. The tours are often cheap and you should expect to pay around 60 soles for the whole day.