You’ve probably heard of Greenwich Mean Time. But if you’re like me, you might not have known its exact definition. When we decided to head to Greenwich, located in South London and suggested by reader Lory, for the day, I figured it was time (get it?) to brush up on my GMT knowledge.

Basically, Greenwich Mean Time is the mean solar time at the Royal Observatory in Greenwich. It was once the international time standard, although it has been replaced for the most part by Coordinated Universal Time (UTC), which is said to be more precise.

At the Royal Observatory in Greenwich, you can view the red Time Ball, one of the world’s earliest time pieces; the UK’s largest refracting telescope; and, most importantly, you can stand on the Greenwich Meridian Line, which represents the Prime Meridian of the world, longitude zero. (Surely you’ve seen pictures taken of people here, smiling happily with one leg on the eastern hemisphere and one leg on the western.)

Of course, we spent so much time in town at the sprawling Greenwich Market, a fantastic mix of arts and crafts and food vendors and shops, and other attractions such as the Cutty Sark, a famous tea clipper ship that is stunning to see in person, that by the time we arrived at the Royal Observatory, it was closed.

Warning: You may get talked into buying a $25 headband when visiting Greenwich Market.

The irony of being late to the home of time does not escape me.

Still, we were able to view the Shepherd 24-hour Gate Clock, one of the earliest electrically driven public clocks, which was installed in 1852.

The Shepherd 24-hour Gate Clock at the Royal Observatory.

And the view alone from the top of the hill where the Royal Observatory is located makes it worth the trip.

View of London from the Royal Observatory.

Build in some time after visiting the observatory to wander Greenwich Park, which is also a great place to spend an afternoon and includes a playground with some of the coolest features we’ve seen.

Seesaw, Greenwich Park style.

I’m still upset we didn’t get a picture of ourselves on two hemispheres, so we’ll definitely be returning. And this time, we’ll be on time.