First came the 7 ancient wonders, but once their glory faded, the world selected a new group of wonders that stand with unmatched engineering prowess. This is Machu Picchu.
Of all of the wonders, new and old, Machu Picchu is perched atop the highest peak in some of the most difficult terrain anywhere around the globe. It was built as a royal estate for a famous Incan warrior, and its impressive engineering has allowed it to survive into modern times.
The Inca engineers behind the mountaintop estate conducted years of research on surrounding springs and soil to determine if it would be a good location to build. Proper water management is what has enabled the amazing wonder to survive so well. It is clear that engineers studied the surrounding springs for a few years because the channels and basins they built for water flow were perfectly sized. It is also evident that the engineers had great knowledge of soil stabilization. Not only did they recognize the need to lay different layers of base soil and materials, but they also covered the entire sides of the mountain in stepping terraces. These terraces both stabilized the mountain soil, and allowed for nearly instantaneous water infiltration into the ground.
While the buildings and structural engineering is incredible at Machu Picchu, it is now known that the Inca engineers would have spent over half of their construction efforts underground in foundation work. Excavation work at the site revealed layers of topsoil followed by fast draining sand and coarse granite gravel. This layout is very similar to modern day stabilized foundations, and it would have allowed for near perfect drainage on the site. Drainage was so important because this area of Peru rains on average 76 inches per year, even as high up as Machu Picchu. Engineers ultimately approached the site with the goal of making it last virtually forever, which is why it has survived so well over the last 600 years.
Apart from the royal estate aspect of the wonder, there were also areas for townspeople to live. Throughout the entire site, every person would have had primitive sewer networks and water drainage networks. The Inca were far superior at water drainage than modern engineers are, in many cases.
The stonework of the site has also been crucial to the survival of the structures and overall site. There was no written language used by the Inca, so all of the construction would have been commanded through spoken word. This is incredible when you look into the precision that stones were laid and buildings were laid out. Of all ancient stonework, the Inca have laid some of the tightest and lowest tolerance stone buildings to date. Apart from the near perfect construction, the layout of the site was also of vast importance.
Engineers made sure that the King’s quarters were the first to get water from the channel that directed the spring water. This water would flow at a maximum of 25 gallons per minute down a slope of about 3%. The stone channel ran all the way through the city. Engineers even designed emergency valves into the open channel as a backup if rainwater overloaded the system.
The hydraulic, structural, and geotechnical aspects of Inca engineering demonstrated through Machu Picchu are simply breathtaking. Even today, there are systems less advanced than what the Incas designed atop this 8,000 foot peak.