Wendel Cox wrestled a book the size of a school desk from its shelf in the Denver Public Library and plopped it in on a table with an audible “thunk” — no surprise for a volume weighing 35 pounds.

It was a vintage Sanford fire insurance map of Denver from 1903 to 1928, showing every structure in the city. Even someone with only a scant interest in history would feel an odd time-tunnel effect eyeing the intersection of Market and 12th streets, where a massive horse stable and feed store stood beside a garage that housed newfangled contraptions called automobiles.

“I love showing this book to students,” said Cox, the Denver Public Library’s senior special collection librarian. “As buildings changed, the maps were updated with paste-overs. They give you some really interesting notations, like whether a building has a night watchman on duty.

“It’s like showing geologic layers of Denver.”

If you’re feeling lost, head to the fifth floor of the downtown branch. It is home to a collection of about 18,000 maps: many historic, some aesthetically gorgeous, and most available for perusal by the general public — no appointment necessary. This being the computer age, many of the maps are being digitized and archived online.

The map collection is the focus of the Booklovers’ Ball, the library’s fundraiser on Oct 9. The 2010 theme: “Explore.”

The collection draws everyone from Pulitzer Prize winners to eminent historians to third-graders, lured by maps that go back centuries.

Thanks to the computer age, we have become saturated with cartographic information. But maps are also windows into who we were.

“Maps are everywhere, and the uses boggle the mind,” said Susan Schulten, associate professor of history at the University of Denver and author of “The Geographic Imagination. “But aside from their use as navigational or analytical tools, maps are fascinating artifacts in and of themselves. They lie somewhere between art and science, a picture and a text, and continually draw us in for their ability to render the landscape in unexpected ways.

“They position us above the landscape, giving us a sense of perspective, even mastery, that can be deeply satisfying.”

Among the prizes is an 1860 military expedition map of the Four Corners region, created when place names were still in flux (Arizona’s Little Colorado River was also dubbed the Flax River).

It’s a large map, covered with what looks like green and gray watercolors. But examine it under a magnifying loupe and you see minute lines invisible to the naked eye: It’s an engraving, a minor masterpiece of that art.

Another treasure is an 1866 map — “Ribbon Map of the Father of Waters” — depicting the Mississippi River from headwaters to delta. It unspools from a canister. Unrolled, it’s about 3 inches wide and 11 feet long. The map is kept in the vault, but a blowup depiction hangs in panels, tapestry style, in a fifth-floor study room.

Some maps are anomalies, such as one from 1692 depicting Baja California as an island. Others are whimsical.

One example is a cocktail napkin from the old Top of the Rockies restaurant, a popular spot in the 1970s. The napkin depicts a fish-eye aerial view of downtown Denver.

“It just walked in one day,” Cox said of the acquisition. “It’s really compelling.”

There are contemporary maps, too, such as the Denver Bike Map. “Fifty years from now someone will be going, ‘Can you imagine? Streets that actually had automobiles,'” Cox said with a grin.

The library spent years as a federal repository for government documents. Among other things, it received every 7.5-minute map in the U.S. These are the maps that depict terrain, roads and structures, and there are about 6,000 of them.

A recent afternoon found Rita Lopez sifting through quadrangles from New Mexico, looking for her hometown outside of Las Cruces.

“I just love seeing the old place names and the topographic lines of the terrain I grew up in,” she said. “It’s like a quick trip back home.”

The collection has entered the computer age. Many of the maps, including those decades-old city plats, have been digitalized by the library and are available online.

The library is at work on its “Creating Communities” project, starting with digital maps for seven Denver neighborhoods: Capitol Hill, Five Points, Park Hill, Barnum, Auraria, West Colfax and University Park.

Cox sees a future where traditional printed maps exist alongside online versions.

“In some cases it makes sense to lay a map out physically in front of you,” he said. “You kind of fall into them. But digitalizing them gives people an access they might not otherwise have.”

Exploring a map room is its own voyage of discovery. “It’s the experience of opening a drawer, browsing through it and finding something you didn’t even know you were looking for,” Cox said.

He is happy to share those eureka moments. “We’re fine with people handling most of these maps, as long as they haven’t been eating a chocolate sundae,” Cox said.

William Porter: 303-954-1877 or wporter@denverpost.com

, which is a fund-raiser for the Denver Public Library, will be held Oct. 9. Cocktails start at 6:30 p.m., dinner and dancing at 8 p.m. The event is held at the DPL’s main branch at 10 W. 14th Ave. Parkway. Tickets can be purchased online at dplfriends.org or by calling 720-865-2051.