What to do in Edinburgh for a day?

[Marax]

We are travelling up to Scotland on Sunday and our first port of call is Edinburgh, for the day.

Any suggestions on things to do for a 12 and 13 year old?

The Surgeon's Hall is pretty interesting, though gruesome in places.

As PP have said, just wandering around is brilliant in August.

Camera Obscura would be brill for the tweens. Maybe check out Dynamic Earth ;)

Camera Obscura at the top of the Mile