An ultra-rare artifact from the founding days of Disneyland is going up for auction. The first map of the park, which Walt Disney drew by hand to help sell Disneyland to investors, is estimated to be the most valuable piece of Disney memorabilia ever auctioned, according to the auction house Van Eaton Galleries.

In the ‘50s, Mickey Mouse, Donald Duck, and Disney’s feature films were already famous, but not quite so famous that investors thought a Disney theme park would be a slam dunk. In 1953, after mortgaging his home and borrowing as much money as he could, Walt Disney went to New York to meet with banks and TV studios about financing his dream park. Knowing that his blueprints might not convince them, he and artist Herb Ryman worked nonstop the weekend before the pitch meetings to sketch out an aerial view of what the amusement park would look like.

A view of Disneyland's Main StreetCourtesy Van Eaton Galleries

ABC ended up giving Disney the funding, and Disneyland was born. The map lived on, too. Disney brought it to meetings with developers and kept it at his studio to inspire his designers. In 1954, he had the map colorized and added a few more sketches, then made it the first promotional image used to sell the park to the public.

The original ended up in the hands of Grenade Curran, a Disney employee whom Walt gave it to after one of the last planning meetings for the opening of the new park. Curran stored the map away, and this is the first time it has appeared in the 60 years since.

The item is going up for auction in June at Van Eaton Galleries in the L.A. area, and is on exhibit to the public until then.