A massive blanket fort will be built in Millennium Square in an attempt to break the world record.
The giant fort is being built in the city centre square between 2pm and 5pm today.
It has to be more than 625.79 square meters to beat the current record and be officially named the world's biggest blanket fort.
Almost 650 blankets will be used in the attempt.
After the fort has been completed, it will be open to the public for free.
Inside they can enjoy food, drink and games for young children.
Once the event is over - the blankets will be donated to a homeless charity.
It is being built by West Yorkshire based company Time4Sleep.
Jonathan Warren, CEO at Time4Sleep said of the attempt: “Building a blanket fort is something that takes us all back to our childhood, no matter how old we are. We can’t wait to host this truly memorable event, smashing the world record and providing the people of Leeds with the novelty of seeing the world’s biggest blanket fort.
“We’re hoping to see plenty of people come down to visit us in the fort and enjoy the games and refreshments that we put on. Whether you’re six years old or sixty, our blanket fort is the manifestation of every childhood fantasy, so you’ll be encouraged to let your imaginations run wild and have a great time when you’re inside!”