Obelisks were markers of time and place, raised by late Egyptian pharaohs in commemoration of anniversaries, victories, and the favor bestowed on them by the gods. They seem outwardly as simple and apparent as their stark planes, but the quarrying, transport and raising of a megalith that weighs as much as 450 tons proves to be as complex as the babble of hieroglyphs that adorn the obelisks' faces.

For this experiment, Egyptologist Mark Lehner joined Massachusetts stonemason Roger Hopkins in search of ancient clues in the original quarries far up the Nile at Aswan. There they confronted one of history's great failures, the Unfinished Obelisk of Aswan, doomed by rock flaws to remain only partially sculpted out of the pink granite. From this failure the team tried to learn how the massive shafts of granite were cut from the rock, dragged to the Nile, loaded on barges and shipped down the river. With the help of ancient technology buff Martin Isler and Egyptian monument expert Ali el Gasab, the team ran straight into the engineering obstacles that stand in the way of raising a massive yet delicate needle of stone to upright stability.

Our team failed the first time. But they're going back to give it one more try. Does someone out there have the method that will help them succeed? On May 19, Mark Lehner responded to questions during a live event, and to additional questions e-mailed to this Web site the following day. Check out the archived questions and answers.