There are today more than 400 billion Lego blocks around the world, it is estimated, or around 50 per person.
But some of those blocks - or the sets they make up - are worth considerably more than others.
Rare Lego sets and minifigures can change hands for north of five figures, with two particularly sought-after models today valued at more than £10,000 each.
As well as being fun to play with, Lego can be a solid investment, with the price rise of limited edition sets often considerably outstripping inflation.
BrickEconomy provides a handy guide to the most valuable Lego sets today, whether they are still factory-sealed or very well-loved, and how their price could increase.
Below are the 14 most valuable Lego sets and minifigures right now, according to BrickEconomy.
They include a 1970s classic, Star Wars merchandise and several exclusive limited edition sets.
Could any of these be lurking in your loft?
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13. 4000012 Piper Airplane - £10,259.04
Just 53 copies of the plane, based on the first aeroplane bought by the Lego Group in 1962, were ever made. They were given to attendees of the 2012 LEGO Inside Tour. A new, sealed set is today estimated by BrickEconomy.com to be worth £10,259.04, with a used set valued at between £1,937 and £2,198. | BrickEconomy/Lego Photo: BrickEconomy/Lego

14. LEGO San Diego Comic-Con 2013 Spider-Man - £13,308.38
This Marvel Super Heroes promotional set was released as part of the 2013 San Diego Comic-Con and given to attendees who won the daily raffle, with only 350 produced. It is today worth an estimated £13,308.38, according to BrickEconomy.com, with a used set valued at between £10,836 and £12,294, depending on its condition. | BrickEconomy/Lego Photo: BrickEconomy/Lego