If you go to Scotland and Edinburgh then you must visit the Edinburgh Castle. The castle is located at the top of the old town and you can just walk there if you live around the central area. If you have a English Heritage membership then entrance is half price. You also get to skip the ticket queue (which was considerably long when we went there) as you buy from the visitor centre and not the ticket counter. Most of the castle is accessible so it a good place to go with your children. There is a 20 minutes tour of the castle every 30 minutes which I strongly recommend. At 1PM everyday they fire a gun so which is worth watching if you can time your cisit correctly. The castle contains the Royal Palace, Scottish national war memorial, a chapel, a siege gun called Mons Meg, a great hall and a dungeon of sorts. You can take photos everywhere except the war memorial and the Royal Palace which houses the Scottish crown jewels. Because the castle sits atop a hill, the view of Edinburgh from the top of the hill is absolutely great. This is one place you must not miss if you go to Edinburgh.