I just checked, and the bedrock is 70 ft below grade. To blast through 841 ft of bedrock is too excessive for a memorial IMO.

I do like the idea of putting a memorial down on the bedrock however. It brings forth imagry of being brought down to the lowest point in our history, then towering up higher than before. The names of the 3000+/- victims could be permantly inscribed into the wall, to be read as one descends to the bedrock floor.

I like Sambo's idea of the reflection pool immensely. Imagine looking down into the depths only to see the reflection of the new towers staring back at you. Incidentally this also solves the problem of drainage.

-Steve G.