 The stone construction that the Incas are famous for. This is considered to be "pillow style" because the rocks are slightly rounded. No mortar is used, and David is showing how a piece of paper can't fit inside the cracks. |
 This shows how many of the rocks are rounded, often at corners of the structures. |
 This is an example of the "cell style" - it's less intricate, but is still accomplished without mortar. It's used in less important structures. |
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