joost5:The Incas of around 1450 CE were expert stone masons. It took a team of 3000 people 20 years
joost5:The Incas of around 1450 CE were expert stone masons. It took a team of 3000 people 20 years to construct this site, quarried from stone 3 miles away. It contained a water tower, grain and other strategic facilities. The Spanish conquistadors demolished most of the structures and repurposed the stones (above ground) for churches and forts.Saqsaywaman Cusco Peru - altitude of 3,701 m (12,142 ft) -- source link