What Are Igneous Rocks and Why are They Used in Monumental Structures?

Igneous rocks are made from hard silicate minerals such as quartz, feldspar, olivine, and pyroxene. Although their hardness makes them rather difficult to work with, they are very resistant to weathering. Monuments made from igneous rocks will last many thousands or years. This is difficult to comprehend in our modern world of disposable culture. Our computers and phones are designed to be obsolete a few years after we buy them, and increasingly works or art and literature exist entirely in the virtual world with no physical manifestation at all. If you were going to design a monument that would last thousands of years, what would it be? As always, you are encouraged to use sketches, photographs, or other illustrations to accompany your 250-300 word response.