Lego is the world's largest toy company but it's gained a reputation for being an expensive hobby. Since 2007, Lego has released dozens of sets that cost over $300.

The most expensive sets cost $850. And prices for vintage Lego sets can reach over $1000.

These high prices have caught the attention of thieves, who in some cases have stolen about $300,000 worth of Lego.

So, how did we get here? How did Lego go from a children's toy to a collector's item? And why is it so expensive?