Ashlar:
Much of the Inca’s work on Machu Picchu, though impressive, is inconspicuous. Ken has estimated that 60 percent of the construction is underground. But what first strikes the visitor is the exquisite stonework of the city’s most elegant buildings. Without mortar, using a technique called ashlar, the Inca fit finely carved granite stones together with such precision that a piece of paper cannot be inserted between them. Bingham called one side of the Temple of the Sun, a long stretch of perfectly spaced rectangular rocks, “the most beautiful wall in South America.” [“How The Inca Built Machu Picchu“, Cody Cottier, Discover (May 18, 2021)
An example:
Source: Wikipedia
