This is the world's most expensive single banknote worth millions of dollars

With its distinctive design featuring oversized green zeros that resemble watermelons, the "Grand Watermelon" note has become one of the world's most coveted and expensive banknotes

In 1890, the "Grand Watermelon" $1,000 Treasury Note was introduced as a part of a group of notes designed to help banks and other financial institutions, not private people, conduct massive, high-value transactions.

There are just seven of the $1,000 "Grand Watermelon" Treasury Notes in existence today, making them incredibly uncommon.

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Institutions own the majority of these, with only three in private collections.

Due to its scarcity and historical significance as one of the first high-denomination U.S. currency notes, collectors greatly prize this note.

The fact that these Treasury Notes, sometimes known as "coin notes," could be redeemed for either gold or silver currency made them special.

This was at a time when conversations about gold and silver standards were influencing U.S. monetary policy.

The note was an easy, straightforward means to settle large financial transactions, but its $1,000 denomination made it extremely impractical for daily use.

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It is quite enigmatic and desirable to collectors today because, on January 10, 2014, it was sold for $3.29 million (£2.6 million) at Heritage Auctions (USA), making it the most expensive banknote ever sold at auction.

It is among the world's most valuable currency notes due to its unique design and rarity, and therefore it is more of a collector's item than an everyday means of exchange.