The Harlequin has been in Watford for 21 years.
Throughout September there will be birthday celebrations - a month long extravaganza in fact!
From the 1st -24th September shoppers will be invited to join in the fun, with the chance of winning fantastic prizes as part of the 'What's in the Box?' competition.
21 lucky boxes are on display around the centre and each one has it's own very special prize. Cryptic clues as to what may be hidden inside can be found in the centre and on Facebook and Twitter.
Choose your lucky number and simply drop your entry into the box or enter online. You can enter as many boxes as you like!
You can find boxes 1 to 20 in the centre from 1st to 18th September with box 21 staying in the centre until Saturday 24th September.
If you are lucky enough to win you will be invited to attend the grand finale on Saturday 24th September, where you will be presented with your prize on stage.
Get hunting for those clues!