Pure wonder ... a window to the past at Machu Picchu.

Machu Picchu. Photo: Reuters

SBS One, 7.30pm

For all the New-Age hooey about ''the Lost City of the Incas'' - that it was some sort of transcontinental spiritual vortex or a landing spot for aliens - one thing is for sure: it's an outrageous piece of engineering. Perched 2430 metres above sea level on a heavily jungled Andean ridge, the site features about 200 structures, each made from colossal blocks of exquisitely cut stone. How the Incas built this in the absence of the wheel (yep, they never quite figured that one out), let alone 3G phones, power grinders and enterprise bargaining, remains a mystery.

This National Geographic documentary is a fairly orthodox retelling of the Machu Picchu story, complete with pan pipes, industrial quantities of conjecture and the promise of an ''astonishing discovery''. Not change-your-life TV but this primer on Inca history is diverting nonetheless.