What is it?

London is a city that refuses to be summed up. Founded by the Romans as Londinium around AD 43, it has burned, been bombed, rebuilt and reinvented itself more times than almost any capital on earth — and every layer is still visible, from a fragment of Roman wall beside a glass tower to Wren's dome of St Paul's rising above the Square Mile. Spend a day here and you might stand where kings were crowned in Westminster Abbey, see the Rosetta Stone in the British Museum, drift past the Houses of Parliament on the Thames, and end up in a 400-year-old pub with sticky floors and a great pint. The city is really a patchwork of villages — bohemian Camden, curry-scented Brick Lane, elegant Kensington, riotous Soho, leafy Hampstead — each with its own accent, food and mood. It sounds like church bells and sirens, black cabs and buskers in Underground tunnels, and a dozen languages overheard on a single bus ride. What makes London unique is that all this history is not a museum piece: it's a working, crowded, gloriously chaotic city getting on with its Tuesday.

Where is it?

London sits in southeast England on the River Thames, roughly 50 miles inland from the North Sea, and is served by six airports — Heathrow and Gatwick being the main international gateways — plus Eurostar trains from Paris and Brussels into St Pancras International. The essential sights cluster in Zones 1 and 2: Westminster, the South Bank, the City, Covent Garden, Shoreditch and South Kensington are all walkable or a short Tube ride apart. May to September brings the longest days, park picnics and outdoor theatre, while December wraps the city in Christmas markets and lights; expect rain in any month and crowds at peak summer.

What makes it worth it?

There's a moment most visitors describe — cresting Waterloo Bridge at dusk, with St Paul's glowing to the east and Parliament lit gold to the west — when London simply floors you. It's the sheer density of things that matter: the Magna Carta, Shakespeare's Globe, Abbey Road, the Crown Jewels, Freddie Mercury's handwritten lyrics, all within a few square miles. People come expecting stiff formality and leave talking about the wit of strangers, the free museums that could occupy a lifetime, the pub gardens on a rare sunny evening. "I thought a week would be enough," is the most common refrain — followed by a return visit. Years later you'll remember not just the landmarks but the small things: the rumble of the Tube, the smell of rain on Georgian pavements, a curry on Brick Lane at midnight, and the strange thrill of walking streets that Dickens, Woolf and Bowie all walked before you.

How accessible is it?

London is one of the world's easiest cities to visit and welcomes around 20 million international visitors a year, with excellent public transport — just tap a contactless card or phone on the Tube, buses and trains, with daily fare caps around £8–9. It is, however, expensive: budget travellers can manage on £80–100 a day with hostels and street food, mid-range visitors should plan £180–300 a day, and luxury hotels start north of £400 a night. The big draws — British Museum, National Gallery, Tate Modern, Natural History Museum — are free, which offsets pricier tickets like the Tower of London (~£35) or the London Eye (~£30); West End theatre ranges from £25 day-seats to £150+. Book major attractions, popular restaurants and shows online in advance, especially in summer. The city is broadly step-free at street level and improving underground, though many older Tube stations lack lifts — check TfL's step-free map if mobility is a concern. Visa requirements vary by nationality; many travellers now need an ETA, so check UK government guidance before booking.