London's Longest Run is here!

Welcome to London 100 - London's longest run.

Central London's first ever 100 mile ultramarathon will be Saturday 10 May 2025. The event starts and finishes in central London and travels north, east south and west past over 100 of the capital's famous landmarks.

Ultramarathons are often in rural, hard to reach locations. We have created London 100 to be an accessible, inclusive event, which doesn't need most participants to travel long distances or to book the equivalent of a small holiday to take part.

We're excited to bring this legendary distance to London for the first time. Make sure you're one of the event's pioneers in our first ever event in 2025. Register your interest to be first to hear about when we launch.