At 2, 300 years old, Chankillo observatory has been described as one of the oldest of its kind in the world — and the oldest in the Americas.... It is a construction of 13 stone towers built atop a hill, and was once used as a calendar.... Only this summer was Chankillo designated a UNESCO World Heritage site.An ancient Peruvian civilisation built it around two millennia before the ascent of another well-known and now famous sun cult — the Incas.It is believed that they completed it at some po