There are so many underrated places, or unknown by foreigns because of the lack of infrastructure, specially transport; no flights or even no paved highways.

Kuelap ruins in the Chachapoyas region is one of them. Besides the ruins there are several archeological sites in the region, with ancient sarcophagi; plus a beautiful nature that includes one of the highest waterfalls, Gocta. Unfortunately there are no regular flights to Chachapoyas and though the roads are mostly paved it's too far from Lima, the best way is to fly to Chiclayo and then go by bus. I've heard there are considering to re-open the airport for large airlines flights again.





The Huaylas Alley (Callejón de Huaylas) or valley is another great place for nature and adventure trips. It's the valley where you can see the most beautiful glaciers and lagoons. It's about 8 hours by bus from Lima, actually not far. There are no flights to Huaraz (the region's capital). And there is also archeological sites like Wilcawain (near Huaraz), or Chavín de Huantar, a great temple of one of the largest culture before the Incas era.
The tour to Chavin is an adventure itself. You must cross the mountains chain to enter another valley (Conchucos), crossing a mountain thru a large tunnel, watching the whole valley near beatiful lagoons and landscapes.