Answer:
The word "obelisk" comes from the Greek word obelos, meaning a dagger. These monuments were thought to look like daggers, with their columns ending in a point. Obelisks are typical examples of ancient Egyptian art; they have an elegant slender form, a square base, and end in a pyramid-shaped point.
In height, as a rule, they are about ten times the diameter of the base. The point was usually sheathed in a bright precious metal, silver or gold, but of these valuable metals was stolen long ago. Because of the layer of metal the columns reflected the sunlight brilliantly and they could be seen from a great distance.
Obelisks were usually carved out of reddish-coloured granite found at Aswan. Sometimes dark grey basalt was used.
The dimensions varied: the tallest known obelisk remains unfinished in a cave at Aswan (about 40m) and the smallest is less than 2 metres in height. They were not merely decorative but stood in front of the temples and were usually dedicated to the sun gods. On many obelisks there are inscriptions in hieroglyphics saying to which gods they were dedicated and to the Pharaoh who ordered their erection.