(CNN) -- Every day seems to bring a new use for Lego, from getting stuck in your boot heel to providing a chew toy for your dog to actually teaching kids how to make things.
Now there's another one: to mark its 150th anniversary, London Underground has created a series of maps of the Tube made entirely from Lego.
You might have to ask the Underground's sponsorship department that, but what we do know is that the maps depict the Tube network at various points in its history.
Each map is made up of more than a thousand Lego bricks and took more than four days to build.
The first map shows how the Tube appeared in 1927.
Another depicts it in 1933, when copies of Harry Beck's renowned diagram of the Underground was first distributed to the public. A version of Beck's design is still used today.
A further map predicts how the Underground might look in 2020.
The Tube is the world's oldest underground railway. When it opened in 1863, steam-powered, gas-lit wooden carriages chugged through the tunnels.
During World Wars I and II, many stations were used as air-raid shelters.
There are also some disused -- ghost -- stations, some retaining original platform furniture and advertising. Some have been used for film shoots and others left to decay gently.
Exactly 150 years after its founding, the Underground now has 402 kilometers (249 miles) of track stretching between 270 stations.
"We hope the maps will inspire the young engineers of the future," said a London Underground spokesman.
The maps will be displayed at Tube stations throughout the summer, if you want to wander along and see one.
We still don't know why they're made out of Lego, though.