Peru is home to many curious mysteries. But this mile-long band of around 6000 holes near Pisco is surely the most confusing of them all.

Where is it?

The Pisco River cuts a swathe of emerald through the exceptionally arid, stony landscapes of central Peru. The city of Pisco receives only 0.06 inches of rain every year, but it is famed for its lush vineyards…and its pisco of course.

25 miles from Pisco lie the Inca ruins of Tambo Colorado, another settlement which owed its existence to the river’s bounty. Built during the reign of Pachacuti, Tambo Colorado served as an important administrative center along the Qhapac Ñan –  much like the sites of Huanuco Pampa and Vilcashuaman which have already been discussed on this blog. Due to the extremely dry climate, the ruins are excellently preserved and they are well worth including on your Peruvian itinerary.

The Band of Holes is located 3 miles from Tambo Colorado, in a relatively flat area that coincides with a narrowing of the river. It was first brought to the world’s attention by an aerial photograph published in National Geographic in 1931, and it is still best appreciated from above.

What is it?

The Band of Holes also known as Monte Sierpe (serpent mountain) and Cerro Viruela (smallpox hill) comprises between 5,000 and 6,000 man-made holes which snake up a hillside for about a mile. The holes have an average diameter of about 3ft and are between 2 and 4ft deep. The band varies in width from 45ft at its narrowest to 70ft at its widest.

As with all mysterious sites, outlandish theories about the holes’ construction abound (aliens predominate, naturally), but UCLA archaeologists Charles Stanish and Henry Tantaleán (who, unlike most other theorists, have actually done extensive research at the site) have a far more prosaic explanation:

“The alternative science websites suggest that the construction of Monte Sierpe was a difficult undertaking. This is simply not true. There are three kinds of “holes,” all quite easy to build for an entity like the Inca Empire. They are not dug into volcanic rock as implied in some of the alternative science arguments. The sides of the hole segments were elevated, with removed soil giving them volume above the surface. A second kind of “hole” was actually dug into an artificial low mound scraped from the sides of the hill. The other “holes” were actually small rock structures (that looked virtually identical to informal storage structures in contemporary sites in the region).”

Stanish and Tantaleán go on to explain how easy it would have been for the Inca empire to construct the entire Band of Holes:

“With a pre-Hispanic technology of stone picks and foot plows, one young man could dig or construct one of these holes easily in about two or three hours on average. Digging holes into the mounded surfaces would have gone even faster. A very conservative estimate is that one worker could easily dig or construct two holes per day. Working in groups, laborers would have been even more efficient. Teams worked in groups of 10, 50, 100, and 500 for local projects such as these. A simple calculation reveals that 10 workers could have made this entire band in 300 days; 50 workers in 60; and 100 workers in a month. Five hundred workers, properly managed, could have knocked this out in a couple of weeks.”

Why did they bother?

They’re not know as the mysterious Band of Holes for nothing, and the short answer to this question is ‘Nobody knows’. Since their discovery in 1931 various experts, amateurs and adventurers have suggested that they were built as vertical graves, geoglyph art, defensive positions and very odd-looking storage containers, to name but a few.

But we turn, once again, to Stanish and Tantaleán for the most plausible theory. They believe that the holes were a place for Inca subjects to leave tribute for the state, in the form of beans, grains and other produce. It was the job of Inca accountants or quipucamayoc (click here to find out more about them) to receive the tributes – not an easy task, given the vast quantity of tribute that Inca subjects were required to pay the state.

Archaeologists at Inkawasi, just 75 miles to the North, have unearthed evidence of an enormous ‘checker board’ which was used to physically separate the tribute into piles, and Stanish and Tantaleán posit that the holes at Monte Sierpe were a local adaptation that served the same purpose. “The curious nature of the different kinds of construction of the holes is now understandable as a means of accounting for different groups and possibly different kinds of goods. Each segment, we suggest, belonged to different tax-paying groups, most likely kin and territorial groups called ayllu.”

To prove their theory they are trying to find traces of ancient pollen or other pieces of plant tissue in the soil. If they find them it will mark a significant step towards putting one of South America’s greatest mysteries to bed, but – if you ask me – it’ll only make the holes more interesting, not less so.

As they say, watch this space…

Photo gallery

These pics were taken only yesterday by SA Expeditions’ Chief Explorer, Nick Stanziano as he treks from Vilcashuaman to Ica along the Qhapac Ñan.

Further reading:

Recent article in Archaeology Magazine

Another, fairly similar, article on Ars Tecnica

Stanish and Tantaleán’s full academic paper

An article about the ‘checkerboard’ discovery at Inkawasi

Another article about the Inkawasi discovery