Machu Picchu is a wonder of architecture. The Incas were amazing at using the pre-existing stone and modeling against it to make houses, walls, or structures. Many times they left large stones in place only to carve stairs into them. Here are some of the impressive examples of their architecture:
Double doorway jams
Carved stairs with shaped stones
Possibly the most perfect rock wall ever!
A jigsaw puzzle of rocks that demonstrate the skill of the masons.
When space was tight, they used flying stairs.