Concord, Mass. ? Strolling on ground where Minutemen and British regulars once skirmished, modern-day visitors to Minute Man National Historical Park no longer have to depend on the occasional mounted sign to imagine Paul Revere’s ride or “the shot heard ’round the world.”

Now, visitors can dial up the past on their cell phones and hear the American Revolution unfolding in their ears.

National Park Service officials hope a new self-guided audio tour, recently launched at Minute Man National Historical Park, will help visitors better understand their surroundings while allowing them to stroll the grounds at their own pace.

The Minute Man National Historical Park is the first in the National Park Service to use cell phones to guide a tour. The technology, developed by Spatial Adventures, based in Ashburn, Va., was first used in March at Historic St. Mary’s City, a Baltimore museum of history and archaeology. It has been used since April for tours of downtown Denver, said Scott Hilton, the company’s chief executive. The concept is growing elsewhere as well: A company called Talking Street offers cell phone tours of Manhattan’s Lower East Side and plans to introduce other locations this summer.

Park officials say the cell phone concept is appealing because it doesn’t require the purchase of equipment, or tracking down audio machines that wander off with visitors leaving the 970-acre park. And cell phone tours allow visitors to take a guided tour even when the park’s two visitor centers are closed.

Three-part tour

The tour, three-quarters of a mile long, is divided into three parts.

In the first section, visitors can learn about the place where Paul Revere was captured and the “politics and economics that led us to start a revolution,” said Lou Sideris, a park ranger for Minute Man National Historical Park.

At the Hartwell Tavern, a homestead and farm where people traveling to and from Boston stopped to share news, visitors learn the role the landscape played in the course of the war and the story of the people who lived along Battle Road, the route the British took when they retreated back to Boston.

Ken Guse and his wife Karen, of Columbus, Ohio, listen to a demonstration of the Minute Man National Historical Park's new cell phone audio tour on their Palm Pilot as they visit the historic North Bridge in Concord, Mass.

The third part of the tour takes visitors to the North Bridge and the Minute Man statue, describing the “shot heard ’round the world,” and how those events are part of the American identity.

The audio presentation includes music, narration, expert descriptions and re-created eyewitness accounts of the circumstances and events of April 19, 1775, when the Colonials fought the Redcoats at the North Bridge, killing four and wounding several others.

It was at the bridge that Americans for the first time killed British soldiers, and where a statue commemorates Ralph Waldo Emerson’s “The Shot Heard ‘Round the World,” the poetic tribute to militiamen including Emerson’s grandfather.

Two of the dead lie buried next to the bridge. Though the battle was merely a skirmish, it was a turning point in the rebellion. For many, the North Bridge is where the Revolutionary War and America began.

Can’t roam free

The fee for the tour is $5.99 for the first 60 minutes, which includes the first two sections, then $3.99 for the next 25 minutes, which is enough time for the third.

About 20 percent of the proceeds will benefit the Minute Man National Park Assn. and will be used for restoring buildings, visitor services, landscaping and structural needs, Sideris said.

Informational material for the cell phone tour advises those who are charged roaming fees to avoid using the tours.

“We don’t want people to have a bad experience by having a big cell phone bill,” Hilton said.

Deana Trefz, 57, and her husband Terry, 60, of Newbury Park, Calif., recently decided to tour the park without the cell phone accompaniment because of concerns about the cost.

“I figured the walk would take us some time and we pay roaming charges. It could get expensive,” Terry Trefz said.

A sign at the entrance to Minute Man National Historical Park in Concord, Mass., welcomes visitors to take a cell phone audio tour. The tour fee is .99 for the first 60 minutes, and .99 for the next 25 minutes.

Standing at the foot of the North Bridge looking over the Concord River, Lee Guse, 61, listened to the tour from his Palm Pilot on a visit to the park with his children and grandchildren, all visiting from Columbus, Ohio.

“It refreshed my memory about the skirmish or the battle and the fact that the patriots gathered on the other side of the bridge,” he said. “I kind of knew it in my mind, but I hadn’t thought about it for years and it’s nice to renew that. It makes me patriotic.”