A copy of an important pre-Revolutionary map of New York City, which offers a detailed look at Lower Manhattan’s layout in 1767, will be auctioned off at Christie’s tomorrow and is on display in Christie’s gallery now. The sale price is estimated at $50,000-$80,000.

The map is often referred to as the “Ratzen” plan because the surveyor’s name, Bernard Ratzer, was misspelled in the printing. After Ratzer did his surveying, he sent his drawing to London, where the engraving was done by Thomas Kitchin. Later, Ratzer did a larger map that included parts of New Jersey and Long Island. A New York printer and bookseller advertised both maps for sale –– “very cheap” –– in 1769.

The “Ratzen” map was the earliest detailed survey of New York City and includes a wealth of information, from the location of churches, shipyards, and ropewalks –– very long, narrow factories where rope was twisted for use in riggings –– to the ownership of different estates. I.N. Phelps Stokes, a developer and architect who in the early 20th century published an important pictorial history of the city, called it “one of the most beautiful, important and accurate plans of New York.”

Before Ratzer’s map, there were “small, less detailed street maps” of the city, the chief librarian of the map division at the New York Public Library, Alice Hudson, said. But there was nothing with this level of detail and accuracy.

“Really, there’s nothing of that caliber that precedes it,” a senior specialist in the books department at Christie’s, Chris Coover, said.

Mr. Coover described Christie’s map as being in excellent condition, with fine color and no stains. Color was added to maps of the period at the buyer’s request, for a supplemental fee, Ms. Hudson, explained. Individuals could purchase maps either as individual plates or bound in custom-designed atlases.

The last copy of the “Ratzen” map that went to auction was sold in New York in 1991 for $8,000, but Mr. Coover said it was described as having defects, like discoloration and abrasion at the folds. Scholars don’t know how many of Ratzer’s maps were printed, and neither Mr. Coover nor Ms. Hudson knew precisely how many survive. “Most important map collections in this country have at least one copy,” Ms. Hudson said. The Library has several copies of both the earlier and later versions of the map. The New-York Historical Society and the Library of Congress also have copies of the “Ratzen” map. It is among a list of maps identified as missing from Yale University’s Sterling Memorial Library. The copy going to auction this week is described as having been purchased from a New Jersey gallery in the 1970s by a private collector, and passing from that person to the present owner.

Most mapmaking activity in the pre-Revolutionary period was in London, Mr. Coover explained, and Ratzer’s map was an English production. Ratzer, a surveyor in the British Army, was commissioned to create the map by General Thomas Gage, who would later become the Royal governor of Massachusetts on the eve of the Revolution and order British troops to march on Lexington and Concord. In 1766-67, Gage was concerned about the unrest in the colonies and wanted a good map of Manhattan in case the British would be involved in fighting there. In fact, the first surveyor Gage commissioned, Colonel John Montresor, did a rushed job because he was so spooked by the anti-British sentiment in New York. “He wrote in his diary that it was a dangerous business, and he felt he was being observed,” Mr. Coover said.

Ratzer’s map shows Manhattan, roughly south of the present-day Houston Street, and a small sliver of Long Island. Among the interesting features are the Fresh Water pond, which was near present-day Foley Square and was then a source of drinking water; the old Dutch fort at the tip of Manhattan, and, running north to the top of the map, “Bowry Lane,” identified as the “Road to Boston,” because it was part of the Boston Post Road. Toward the east can be seen the farm belonging to “Rutgers” –– Henry Rutgers, a philanthropist who later made a large donation to Queen’s College in New Jersey, which was subsequently named after him. Below the cartouche in the upper-left, dedicating the map to the governor of New York, “His Excellency Henry Moore,” a key identifies numerous churches, City Hall, the Free English School, the College, the Prison, the Poor House, the Barracks, etc.

One feature of 18th-century New York is notably absent. “It doesn’t name the African American burial ground, or Negro burial ground, which is named on other maps of the period,” Ms. Hudson said. The burial ground was just north of City Hall. “That’s interesting to me –– that it’s not a fact in this person’s mapmaking.”