I wonder why the muzzies havn't torn it down....yet.
They have, it's just taking a long time for the process to complete itself.
The Great Pyramid was originally encased in a smooth outer casing of incredibly durable polished white limestone, whose blocks were fitted to amazing tolerances and joined by an equally amazing and strong cement (which we don't fully understand today). Also, the original entrance had been so carefully sealed that even its location had been lost. At the time when Julius Caesar and Mark Antony were battling over Egypt and Cleopatra, no one had been inside the Pyramid for thousands of years, or remembered where the entrance was.
As a result, for thousands of years the Great Pyramid had been effectively "air tight" and immune from anything more than superficial deterioration. The ancient Egyptians even had a saying: "Time conquers all, but Time fears the Pyramid."
All of this changed with the coming of Islam and the Arab conquest of Egypt. In 820 AD, the ruler of Cairo, Abdullah Al Mamun ordered his men to bore a tunnel into the pyramid to search for chambers and treasure. The opening of this passage allowed air and moisture to begin penetrating the pyramid.
Then, in 1356, following an earthquake that leveled Cairo, the Arabs stripped the pyramid of its casing of polished stones to rebuild mosques and fortresses in the city. This has exposed the softer building blocks underneath to weathering, and gave us the familiar "stair-step" sides to the pyramid which allow visitors to climb to the top. In ancient times the smooth, sharply-angled sides of the polished limestone casing were impossible to climb.
The bottom line is, the Great Pyramid will still endure for a long time, but thanks to the Arabs it is crumbling and deteriorating far more rapidly than it would ever have had its protective casing not been breached.