Drottningholm is one of the several castles/palaces1 currently owned by the Swedish royal family, situated as the name implies on a medium-sized island 11 km west of central Stockholm. It used to be a country retreat, but its close proximity to Bromma Airport has assured the gradual encroachment of the city in modern times. Even so, the palace itself is set on the water in the midst of a substantial bit of parkland, so it's much more laid back than the Royal Palace in Stockholm itself; it was for precisely this reason that the King and Queen made Drottningholm their official residence in the early 80s, not wanting to raise their kids in the middle of one of the city's busiest neighborhoods. It's still the family's residence for most of the year (except in high tourist season, when they retreat to an island in the Baltic), although they obviously tend to stick to the private wing, so there's little chance of running into them when you visit.
Well, most days, anyway. By chance, we happened to go on a day when some of the Queen's relatives were having a christening in the palace chapel, with the family in attendance. The downside of this was that we couldn't tour the top floor, as they were using it for the reception; the upside was that, as we waited for the English language tour to start, Princess Madeleine and Prince Carl Philip walked right past us on their way to the chapel, followed a few minutes later by the King and the Crown Princess herself, Victoria2. No sign of the Queen (doubtless hanging with her visiting family members), but Victoria smiled at us and waved, so that was nice.
More interesting was the theater, a restored 17th century opera house. It's a working theater, but the stage and interior have kept their original style and function, so they still use all of the original special effects machinery (they have had to update the lighting a bit, although they've done a good job replacing the candles with some impressive fakes). The seating hasn't changed, either, so it's remarkably uncomfortable; what's more, when the theater was built the seating capacity was limited by the size of the ladies' hoop skirts, which means that now it seats twice as many people as it was designed to do, with no concomitant increase in oxygen flow. A four hour opera watched from uncomfortable seats, with no temperature control and nothing to breathe? Where do I sign up?
1 The Swedish word is slott, which unfortunately covers a sort of broad range of concepts in English. The massive royal palace in Stockholm is Kungliga Slottet, but it can also mean 'castle.' It's also used to describe the manor houses which dot the southern Swedish countryside, some of which are large and impressive enough that they might merit being called a small palace in English; more often than not, they're what I would call 'big houses.'
2 Some time ago the law was changed in Sweden so that the royal couple's oldest child became the heir to the throne, irrespective of sex. So despite having a younger brother, Victoria is set to become Sweden's first reigning Queen since Ulrika Eleonora abdicated in 1720. Leaving Carl Philip free to spend his time driving race cars and taking pictures of flowers.