Friends fan? We bet you didn't spot this in Monica’s kitchen

We don't have a bad word to say about Friends. We have laughed hysterically and we have cried terribly with them for the past 20 years.

We LOVE everything from the genetically-gifted class of actors to the unique apartment interiors.

However, there is just one slight, teeny-tiny problem with the set - Monica's apartment window.

You know the one we mean, that tiny box window above the sink. Well, have you ever noticed something funny about the view?

By delving into the archives, Hello Giggles has found that Monica's window appears to be the chameleon of the city - the view quite literally changes!

In the early episodes, where Pheobe had curly hair and Rachel was a runaway bride, the window looks out onto a typical cityscape of neighbouring roofs and fire escapes.

Then suddenly, between series four and five, a brick wall appears, completely blocking the city view! It's as if constructors built a new high rise right on the gang's doorstep and they didn't even notice.

On this new, mysterious brick wall we can see blurry reflections from neighbouring windows and later on a washing line even appears...

We are still baffled by the brick but we'll play along.

But then something else appears - a wrought iron balcony!
Monica and the crew seem to have been doing some serious balcony maintenance work and haven't even told us.

In a later series (Monica now has long hair), the window reflections have disappeared and a solid window has appeared in the bottom right-hand corner!

Now it gets really weird... the window outside even moves in a later series.

It's seriously weird, but did YOU notice?