Despite the exhausting crowds and long climbs up stairways, this is one of Britain's finest historical attractions. Who would not be fascinated by a close-up look at the crown of Queen Victoria or the armour (and prodigious codpiece) of King Henry VIII?
The buildings of the Tower span 900 years of history and the bastions and battlements house a series of interactive displays on the lives of British monarchs, and the often excruciatingly painful deaths of traitors. There's easily enough to do here to fill a whole day, and it's worth joining one of the highly recommended and entertaining free tours led by the Yeoman Warders (or Beefeaters).
Make the Crown Jewels your first stop, and as early in the day as you possibly can: if you wait until you've pottered around a few other things and generally got your bearings, the queues are usually immense. The other big draw to the tower is the Royal Armoury in the White Tower, with its swords, armour, poleaxes, halberds, morning stars (spiky maces) and other gruesome tools for separating human beings from their body parts. There's also a redisplay of the Line of Kings – an original exhibition dating back to the 1680s – which includes wooden horses carved by Grinling Gibbons, Henry VIII's armour and a scale model of tilting knights. Kids are entertained by swordsmanship games, coin-minting activities and even a child-sized long bow. The garderobes (medieval toilets) also seem to appeal.