If it was good enough for him, it is good enough for me. It is only a few kilometeres outside of the city of Cajamarca and the taxi fare from the city centre was acceptable, about £2.50 each way.
There is also an information centre, which has a few artifacts and a photographic exhibition of almost everything of interest in the Cajamarca area. I was shown around by José who patiently explained things to me. Fortunately for me, he did not speak as rapidly as most of the local people.