Westminster Cathedral

The sheer red-and-white striped brick hits you first as you round the corner onto Ashley Place. Westminster Cathedral is genuinely massive - Victorian neo-Byzantine architecture that feels less pious prayer hall and more like someone decided to transplant Istanbul to SW1. You're inside a space that's properly awe-inspiring: soaring columns, dim lighting, and a vaulted ceiling that makes your neck ache looking up. The craftsmanship is extraordinary if you care about that sort of thing, though the interior feels deliberately unfinished in places - left bare brick where mosaics were meant to go.

Walking around takes perhaps forty minutes at a sensible pace, longer if you're the type to sit and soak it in. The crypt is accessible and worth poking around if you're interested in Catholic history, though it's fairly austere. Kids will find it impressive for about twenty minutes before restlessness sets in.

It's free to enter, which removes any excuse for missing it. Go on a quieter weekday morning if possible - Sunday sees proper crowds. The cathedral's well positioned for a London break, particularly if you're based at Lovat Parks just north of here, giving you easy access to central attractions without the tourist mill of Westminster Abbey across the way.

Honestly? If you're already exploring central London, don't skip it. The architecture alone justifies thirty minutes of your time, and there's a genuine sense of scale that most London buildings don't manage.