Tate Modern

The converted power station on the South Bank is impossible to miss - that massive brick chimney towers over the Thames like an industrial sentinel. Inside, six floors of contemporary art spread across what used to be turbine halls, and the sheer scale of the spaces is half the appeal. I spent a good three hours there and could easily have stayed longer.

The collection shifts regularly, so repeat visits actually make sense. You'll find everything from installations that make you think "what on earth is this?" to paintings that genuinely stop you in your tracks. The building itself is the star sometimes - those enormous open galleries with cathedral-like ceilings give artworks breathing room you rarely see elsewhere.

It's free to get in, which is brilliant, though donations are encouraged. Families with teenagers will get more from it than younger kids, unless you're lucky enough to catch a family-focused exhibition. Serious art types will spend a full day here; casual visitors can dip in for an hour or two without guilt.

The Turbine Hall - that cavernous ground-floor space - hosts special installations that change regularly. Check what's on before you go. Queues can get mad during peak times, so morning visits are smarter.

If you're staying at Lovat Parks nearby, the Tate is a quick tube ride into central London. It's the kind of gallery that justifies a whole day in the city, breaking things up nicely if you've got a week at the park.