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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1. 4000008 Villy Thomsen Truck - £5,009
The 4000008 Villy Thomsen Truck, released in 2013, was an exclusive set with three minifugures which was given to attendees of that year's LEGO Inside Tour. It was based on the first truck the Lego Group used to transport products, purchased by the company in 1958, and only 43 sets were produced. Its rarity means an unopened set is worth £5,009, according to BrickEconomy.com. Used prices for the Villy Thomsen Truck range from £155 to £190, depending on the set's condition, with an average price of £159 for those in good overall condition. | BrickEconomy/Lego Photo: BrickEconomy/Lego

2. 1584 Knight's Challenge - £5,220.32
This 132 piece set showing a jousting scene, with eight minifigures including members of the Crusaders and the Black Knights, was released in 1988. A sealed set is today estimated by BrickEconomy.com to be worth £5,220.32. Used prices for the Knight's Challenge range from £192 to £284, depending on the set's condition, with an average price of £236 for those in good overall condition. | BrickEconomy/Lego Photo: BrickEconomy/Lego

3. 6399 Airport Shuttle - £5,603.04
This 767 piece Town set with nine minifigures, also called International Shuttle, was released in 1990. It included a red double car monorail powered by a 9V engine. A sealed set is worth an estimated £5,603.04 today, according to BrickEconomy.com, with its value forecast to soar by more than 36 per cent over the next five years to £7,635.27. A used set is worth between £661 and £900, depending on its condition. | BrickEconomy/Lego Photo: BrickEconomy/Lego

4. 71001-19 Mr. Gold - £5,787.34
Mr. Gold is a Series 10 minifugure released in 2013 and containing eight pieces. Only 5,000 were produced, and BrickEconomy.com estimates that an unopened Mr.Gold is worth £5,787.34, with a used one fetching between £2,424 and £3,109, depending on its condition. | BrickEconomy/Lego Photo: BrickEconomy/Lego