Limestone is a sedimentary stone created from
crystalized forms of calcium carbonate deposits.
Many limestones are composed
from skeletal fragments of marine organisms such as coral or
foraminifera.
Some limestones do not
consist of grains at all, and are formed completely by the chemical
precipitation of calcite or aragonite (i.e. Travertine).
Many landmarks across the
world, including the Great Pyramid and its associated complex in Giza,
Egypt, are made of limestone.
Limestone is readily
available and relatively easy to cut into blocks or more elaborate
carving.
It is also long-lasting and
stands up well to exposure.
However, it is a very heavy
material, making it impractical for tall buildings, and relatively
expensive as a building material.