A significant piece of California history is going up for auction later this month.

Auction house Bonhams will present what it’s calling “the most important 18th century map of California” during an auction on Oct. 25.

The original manuscript map of coastal California is signed by Miguel de Costansó, a Catalan cartographer and engineer for the Portola Expedition. The expedition was the first exploration of what is now California by a European nation and is regarded as the beginning of Spain’s colonization of California.

As engineer on the expedition, Costansó created the first land-based maps of the California coastline.

The map, which was scribed in Mexico on Oct. 30, 1770, is the first map to depict the San Francisco Bay.

There are three versions of the map, according to Bonhams. The first is a manuscript that does not depict San Francisco Bay, the second is the manuscript that is up for auction, and the third is a 1771 printed map that was produced in Spain using the second manuscript.

“The map was created in conjunction with Costansó’s written report of the expedition, published in 1771 as Diario Historico de los viages de mar, y tierra hechos al norte de la California, the first book on California and itself a rarity,” Bonhams said.

The most important 18th century map of California is being auctions by Bonhams as part of its Exploration and Travel Literature, featuring Americana sale in New York. (Bonhams)
The most important 18th century map of California is being auctioned by Bonhams as part of its Exploration and Travel Literature, featuring Americana sale in New York. (Bonhams)

Bidding for the one-of-a-kind piece of California history will begin at $500,000. The auction house expects the map to be sold at a price between $600,000 and $800,000.

The Costansó map is part of a series of rare and important documents of American history that are being auctioned this month as part of Bonhams Exploration and Travel Literature, Featuring Americana auction.

Also featured in the auction is a subpoena for then-President Thomas Jefferson. It was the first subpoena to be issued to a sitting president, in which Jefferson was requested to produce evidence in the case of treason against Aaron Burr.

Burr was the third vice president of the United States and an original Founding Father who was arrested and accused of high treason for attempting to raise an army to secede the Louisiana Territory and western states from the United States.

The subpoena document is expected to sell for a price of $200,000 to $300,000.

There’s also a copy of the first federal copyright law signed in 1790 by Jefferson during his time as the nation’s secretary of state. That document is estimated to be worth more than $100,000.