Guyven says there is treasure buried under the second tower to the north, just outside the Keep (Act III). Although pressing Z doesn't highlight anything there, if your character stands right at the corner of that tower, a bunch of blue lights rise up from that corner of the tower (where it meets the wall), so that must be where the treasure is, but I haven't figured out any way to dig it up. Has anyone figured this out? (NWN2)

Never mind. I found the answer here (the location of the treasure was not where I thought):

http://www.gamebanshee.com/neverwinternights2/walkthrough/crossroadkeep-yourcontrol.php