The first culture in the area was the Moche, dating from 100BCE to 850CE. It's main sites are the Huacas (temples) del Sol y de la Luna, two adobe pyramids separated by a plain on which the people lived. The larger huaca, del Sol, is currently being excavated and was the administrative center. The smaller huaca, de la Luna, was the religious site.
It also became clear to me here how the ruling priests used gold and silver, the possession of which was tightly controlled and confined to the use of only the highest castes of priests and nobles, to wow the populace. The pyramid is about 150 feet high and overlooks the main plaza where the population came for events. The chief priest would appear on the top level of the pyramid covered in gold and silver, including the face and a large headpiece, reflecting the sun. He would have been quite an impressive sight in an otherwise drab setting.
Something I found very interesting here, and it is also true of places like Cusco, is that in spite of being one of the largest cities of the Inca empire, there is not a single thing left in Cajamarca from the Inca time except for the room where Atahualpa was held hostage. Everything else was razed. For those who don't remember the story, Atahualpa told Pizarro he would fill the room twice with silver and once with gold as ransom if Pizarro would release him. The precious metals were delivered, Atahualpa was garroted, though after he had been baptized.
Cajamarca is another city that has done a great job of retaining its colonial center and sense of character. The Plaza de Armas (the name of the central square in every city in Peru) is still a meeting place where people hang out and converse. There is a buzz of activity and business, it isn't just a staid museum piece.
There are a couple of good churches, the Catedral Santa Catalina and Iglesia San Francisco along with the Belen complex with a nice chapel, museum and 16th century hospital. At the top of the hill in the picture on the right is a carved rock seat said to have been used by Atahualpa to look down over the city.
This is the only structure remaining from Inca time, quite a poke in the eye of the Inca if you ask me. If you look at the picture to the left, you will see a sign on the wall. This is the height to which the room was filled with gold and silver. The king of Spain was initially upset with Pizarro for taking it upon himself to kill Atahualpa since regicide was something a sitting monarch couldn't take lightly. However, when the gold and silver started arriving, the king decided to make Pizarro governor of Peru rather than punishing him for the crime.