A rare piece of artwork has just become the most valuable Harry Potter item ever to be sold after fetching £1.5 million ($1.9 million) at a recent US auction.

The item sold was an original watercolour piece that provided the front cover for the first edition of Harry Potter and the Philosopher’s Stone , published in 1997. Illustrator Thomas Taylor was only 23 years old when he painted the now iconic image of Harry arriving at King’s Cross, standing in front of the Hogwarts Express on Platform 93⁄4 . It was first auctioned over 20 years ago in 2001, the year that the first Harry Potter film was released – at that time, it fetched just over £85,000 (£155,000 adjusted for inflation).

But with Harry Potter now one of the biggest media franchises in the world – with a new TV show on the horizon – that price has only gone up in the last two decades. It was expected to fetch somewhere between £300,000 and £500,000 ($379,000 and $630,000), but Sotheby’s auction house said was the highest price ever estimated for a Harry Potter item. But during the auction, the price quickly went past estimates and eventually fetched more than three times the expected amount, with the auction finally closing at £1,500,000.

The painting, which took two days to complete after Thomas read the original manuscript, was painted with watercolours before outlines were drawn on with black pencil. Bloomsbury, who published Harry Potter and the Philosopher’s Stone, were sent pieces of work .