Estimated length, in miles, of the road system, which fed off two main roads north to south, one along the coast and the other through the Andean highlands.
Modern-day countries traversed from north to south by the roads: Colombia, Ecuador, Peru, Bolivia, Argentina and Chile.
Approximate number of years the road system was in use until the Spanish invasion of 1532. Number of earlier cultures whose routes were adapted by the Incas: Wari, Tiwanaku and Chimu.
Height, in feet, of the highest mountain pass on the 20-mile spur to Machu Picchu.
Length, in meters, of the most famous rope suspension bridge, made using braids of reed or grass. It crosses the Apurimac River near Cusco.
Objects in the show, including gold ornaments, shell necklaces, silver and gold figurines, stone carvings and textiles.
Estimated age of oldest artifact on display: a ceramic stirrup-spout bottle from the Chavin culture.
Regions that made up the empire: Chinchaysuyu, Antisuyu, Collasuyu and Contisuyu, with the capital of the regions, Cusco, in the center of what is now Peru.
Number of years indigenous people have been continuously remaking a suspension bridge north of Cusco.
Length, in feet, of a rope suspension bridge to be built on the National Mall for the current Smithsonian Folk Life Festival.
Days left in the Smithsonian Folklife Festival Marketplace in the museum’s Potomac Atrium, closing July 12. Years that curators Ramiro Matos and Jose Bareiro spent researching the exhibition.
Months the exhibition will be open at the museum.
The Great Inka Road: Engineering
an Empire Through June 1, 2018, at the National Museum of the American Indian, Fourth Street and Independence Avenue SW. 202-6331000. nmai.si.edu.