Pre-Inca Ruins in Peru
The coastal pre-Incan ruins in the north of Peru are some of the most interesting sites I've ever visited. Most of them are newly discovered, and there are active digs at some. Because of this, you can see areas of a site that were unknown just a few months before your visit. When I asked one guide why we couldn't get as close to a mural as we had to other sections, she told me that they were still working on uncovering the rest of the mural.
The Incans apparently copied their irrigation systems from the coastal people, who lived in the desert and brought their water in from the mountains.
Serval of these sites and a couple of excellent museums are around Trujillo, a northern coastal city. I visited them using local transportation, with no difficulty. Among them are Chan Chan, on the road to the beach resort of Huaco.