Meanwhile, here's a site devoted to correcting errors about the chapel in The Da Vinci Code.
LATER: Well, we didn't find the Grail or the Templar treasures. On the way we started to suspect that the reason no one had found them was that no one had ever been able to figure out the directions to the place. But we did get there eventually, and the return trip was easier, since all I had to do was follow signs to the Forth Road Bridge to get back to familiar territory.
In any case, the chapel itself is a beautiful piece of architecture which has countless biblical themes and stories encoded in it. As for the Grail, etc., my son found a number of promising hollow-sounding spots in the walls and floors, but I didn't let him get the pry bar from the car to investigate further.
Unfortunately, it is forbidden to take photos inside the chapel, but I do have a few from the outside. Click on any of them for a larger image.
The effect is spoiled a bit by all the scaffolding, but having the whole thing as rubble on the ground would probably spoil it more.
Close-up of a gargoyle or the like above the entrance.
A newer part of the architecture on one side.
The good thing about the scaffolding was that it could be climbed on, so we got a closer look at the outside upper level than we would have otherwise. This is a stained glass window containing St. George. The sun is shining through it from the other side, so you can see part of it in mirror inversion pretty well.
On the exact opposite side of the chapel is St. Michael's window, but the direct sunlight shining on the outside shows very little.
The gift shop was full of nonsensical tomes about Solomon, the Grail, the Templars, etc.
We didn't make it down to Roslin Castle, but you can catch a glimpse of it here in the center of the photo.There are lots of photos of the inside of the chapel at the Rosslyn Chapel website (here). The chapel was freezing cold and after a while I started to wish I had worn triple socks instead of just double. So it would have taken a lot longer than we had patience for to look closely at all the engravings, but I noticed one right away and it was my favorite of those I noticed. It is a horned Moses holding one of the tablets in one hand and Aaron's rod in the other. (For more on Moses' horns, go here and keep following the links back.)
Also, with reference to the Da Vinci Code website above, Dorothy King e-mails, "Isaac Newton's Tomb in Westminster Abbey also does not have an apple ... LOL"