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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9. LEGO Star Wars Miniland Figures - £7,147.54
This promotional set including Han Solo and Chewbacca figures was given to guests attending the 2011 LEGO Collectors Party at the International Toy Fair in New York in February 2011, with only 125 produced. A new and sealed set is today valued by BrickEconomy.com at £7,147.54, with a used set worth between £5,156 and £6,603, depending on its condition. | BrickEconomy/Lego Photo: BrickEconomy/Lego

10. LEGO Star Wars Han Solo Indiana Jones Transformation Chamber - £8,016.35
This exclusive 56-piece promotional set was released in 2008, with only 100 given out to guests at that year's New York Toy Fair. The minifigures of Han Solo and Indiana Jones are mounted on a rotating platform, making it appear like one is transforming into the other. A new, sealed set is worth an estimated £8,016.35, according to BrickEconomy.com, with a used set valued at between £6,365 and £7,221, depending on its condition. | BrickEconomy/Lego Photo: BrickEconomy/Lego

11. 106 LEGO UNICEF Van - £9,094.65
This 54-piece Town set with one minifigure was released in 1985 with only 100 made. It was a promotional set made in collaboration with UNICEF (the United Nations Children's Fund) and available via LEGO Club in Canada. A new, factory-sealed set is estimated by BrickEconomy.com to be worth £9,094.65, with a used set valued at between £471 and £791, depending on its condition. | BrickEconomy/Lego Photo: BrickEconomy/Lego

12. Ole Kirk's House - £9,782.56
This exclusive 910-piece model of Lego founder Ole Kirk Kristiansen's house was released in 2009 and given to attendees of the 2009 LEGO Inside Tour, with only 32 hand-numbered copies created. This set should not be confused with the similar set 4000007. A new and sealed set is estimated by BrickEconomy.com to be worth £9,782.56 today, with a used set valued at between £7,965 and £9,037. | BrickEconomy/Lego Photo: BrickEconomy/Lego