The largest known Egyptian obelisk is called the “unfinished obelisk”, which today can be found exactly where it was once semi-carved from the solid bedrock. This stone block was intended to be a 120ft / 36m tall obelisk. It is estimated that a block of granite this size would easily weigh more than a 1000 tons, some geologists have suggested a figure in the region of 1100 tons – 1150 tons.The obelisk's creators began to carve it directly out of bedrock, but cracks appeared in the granite and the project was abandoned. Originally it was thought that the stone had an undetected flaw but it is also possible that the quarrying process allowed the cracking to develop by releasing the stress. The bottom side of the obelisk is still attached to the bedrock. The unfinished obelisk offers unusual insights into ancient Egyptian stone-working techniques, with marks from workers' tools still clearly visible as well as ochre-coloured lines marking where they were working.It is now known that the main tool employed for carving the granite were small balls of Dolerite which is a mineral harder than granite, as seen at the open air museum/quarry at Aswan, Egypt today. The discovery of this obelisk and several others in their unfinished states allows us to see how they were made. The means of separating the stone from the bedrock was a common technique used around the ancient world, in which small cavities were made in the stone, which were then filled with wood, which was soaked in water causing it to expandDuring the earliest ages, the Ancient Egyptians knew the so-called " Pn-pn", which was a pyramidal stone with a pointed top and according to their beliefs the "Pn-pn" symbolized the primeval hill from which the world first appeared. Then, in the course of time, this Pn-pn evolved to be an obelisk usually made of granite with a pyramidal shape on top.During the 5th Dynasty, the obelisk began to play an important role inside the temples of Ra; the obelisk being a sacred symbol of the cult of the sun. They were erected on a great base in an open court, and then as the suns rays fell on its pyramidal top, the bright light filled the Temple, giving the people a symbol of the power of the sun. One of the most important obelisks, which still stand in pride in the district of El Mataraya, was erected in front of the entrance of the vanished temple of Re at Heliopolis. King Senwosret I, to commemorate the ceremony of the "Heb-sed", dedicated it to the temple.In the New Kingdom, especially at the time of the 18th and 19th Dynasties, the Kings used to erect obelisks in front of the different temples for religious and political reasons.