GUESS 25...

Wimbledon was the first tennis tournament in the world. It takes place over two weeks in June and July and it is still played in grass. It is one of the four Grand Slam tournaments . The other ones, as you probably know, are Australian Open, Roland Garros and US Open.

But Wimbledon still follows some traditions:

the Royal patronage
the absence of advertising in court

the third one has to do with this photo...

and the fourth one? Have a look at this photo, it will give you a clue.