This is the big gun, sightseeing-wise—literally. The One o'clock gun is fired every day except Sunday from the battlements, a tradition begun in 1861 to give ships navigating the Forth a time check. Then there's Mons Meg, the 15th-century canon. Edinburgh castle dominates the skyline from its rocky outcrop towering above the jumble of medieval tenements, a brooding presence gazing down over the gracious Georgian New Town. This ancient stronghold has history seeping out of the stonework, with an undeniable "wow" factor. It's big, it's bold, it's bolshy,     and the view from the battlements is (almost) worth the hefty price tag in itself— although you could climb Arthur's Seat for free, of course.  If you're a first-timer to Edinburgh, you'll probably want to tick this one off, but go early to avoid the crowds. Two or three hours should be enough time to traipse through the Great Hall (with its hammerbeam roof dating back to 1511); the Royal Palace, home to the royal family until 1603; and check out the Stone of Destiny, Crown Jewels, and St Margaret's Chapel (the oldest building in Edinburgh, which dates back to 1130); and all the military paraphernalia, including the National War Museum, Regimental Museums, prisons, and the moving Scottish National War Memorial.  You'll want to get your money's worth. And at the price, lets face it, you probably won't be coming back in a hurry. It's not the easiest attraction to navigate if you have a disability—there are all those cobbles for a start, and steep hills. But there is a mobility vehicle and a number of wheelchairs—although the chapel and prisons have narrow entrances.