The quarries of Aswan have been in use since the 6th Dynasty. Even today, there are gravel pits nearby and the buildings of Aswan meander up the hill. Remarkably, the unfinished obelisk remains in place where it broke some thousands of years ago. It would have been the largest known obelisk, but apparently a fault in the rock caused it to crack while it was being excavated and it was abandoned. The ancient Egyptians excavated stones using diorite orbs, some of which are displayed at the quarry. The bowl-like depressions seen in the rock face are the result of the repetitive grinding of stone against stone. The regular holes were used to separate blocks of stone; wooden wedges were pounded into the holes and kept soaked. As they expanded, the rock separated.