Multiple historians who specialize in architectural studies have dedicated a lot of their time and knowledge to figuring out how ancient groups of people who did not use advanced tools or even the wheel could create such structures. The most advanced chisels and hammers of the time would have been created from copper, stone, and wood. With these simple hand tools, people dug granite, andesite, and porphyry out of quarries. After transporting them to the final locations, they then carved them with smooth precision so they would fit together almost seamlessly.
What techniques could these ancient experts use to make such flat and smooth surfaces, exact angles, and joints that would not allow a single blade of grass to squeeze between? Historians can only guess about some of the methods that allowed for such unique stone cutting and building styles.
Besides the building details that still give modern people pause, another incredibly distinctive trait of megalithic structures found in the Andean plateaus is the vitrification of some of the stones. Although vitrified means to essentially transform something into glass, the stones themselves are not chemically altered. Instead, they are somehow changed to have an exceptionally smooth, shiny, and reflective surface. It allows for a high degree of light reflection that is not usual in granite or andesite.
Now, it is possible to use modern tools and polish the stone so that it reflects light and even figures most successfully. Ancient people use abrasive sand and powdered rock from courts and other materials to polish decorative stones as well. However, none of these methods would be able to vitrify the rock as successfully as these ancient people did. Not only was the surface highly reflective, it was altered in an outer layer that could not be explained by any conventional means.