PHILADELPHIA (AP) — With muskets polished, flags aloft and one very commanding tent in place, Philadelphia’s Museum of the American Revolution is at the ready.

After nearly two decades of planning, the museum that tells the dramatic story of the founding of the United States opens April 19, the anniversary of the shots fired at the battles of Lexington and Concord in 1775 that ignited the war.

The museum also reveals how a diverse population — including women, Native Americans, and enslaved and free blacks — helped push the revolution and shape the conversation about liberty. It does so with interactive exhibits, theater presentations and large-scale replicas, in addition to original artifacts and the occasional whiff of gunpowder.

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It’s 118,000 square feet of history, but here are a handful of can’t- and shouldn’t-miss exhibits, details that surprise and small gems not to pass by:

WASHINGTON SLEPT HERE

The museum’s marquee exhibit is George Washington’s headquarters tent, which served as his office and sleeping quarters throughout much of the war. Sometimes described as the first Oval Office, it hosted discussions with the likes of Alexander Hamilton and witnessed dramatic moments like the 1781 Siege of Yorktown, the last major battle of the war.

It was also the subject of a custody battle.

After Washington’s death, the tent eventually passed to a great-granddaughter, who happened to be married to Robert E. Lee, the Confederate Civil War general. But Union troops ravaged Lee’s mansion at Arlington, Virginia, and seized the tent. After the war, a legal battle began over ownership of the tent, which was returned to the family in 1901.

Lee’s daughter sold the tent about 100 years ago to the Rev. W. Herbert Burk, an Episcopalian minister from Valley Forge who dreamed of creating a Revolutionary War museum. The museum acquired it in 2002.

Visitors enter a theater for a narrated audio-visual presentation that reveals the tent behind shatter-proof glass and in front of changing landscapes and seasons.

Don’t blink, or you’ll miss the shadow of Washington moving within by candlelight on the tent’s left side.

BRIDGE OVER REVOLUTIONARY WATERS

A section of the North Bridge, site of a fateful confrontation between colonists and British regulars, gives a tangible sense of “the shot heard ’round the world.”

The Battle of Lexington Green was the first military engagement of the war, on April 19, 1775. Eight men in the outnumbered Lexington militia were killed by the British and nine wounded, and the group fell back. But several hundred minutemen later engaged the British at North Bridge in Concord, forcing a marathon-like retreat of the British to Boston.

Ralph Waldo Emerson later immortalized the first shot fired in that skirmish as “the shot heard ’round the world.”

The bridge was torn down in 1788 for a more modern span, but several pieces of the original were found in the Concord River in the 1950s.

LIBERTY TREE

Visitors can put their hands on an actual piece of history with the museum’s 18-foot-tall replica of Boston’s Liberty Tree, the first in America. There were once 13 liberty trees — one in each of the original Colonies — where the Sons of Liberty met and plotted the Revolution.

Visitors can walk beneath the branches and read broadsides like those posted on such trees in the build up to the Revolution and period reproduction lanterns made by tinsmiths at Colonial Williamsburg will hang from the branches evoking 1766 Boston.

An actual piece of the Annapolis, Maryland, Liberty Tree is embedded on the display, and passers-by are encouraged to touch it.

The Annapolis tulip poplar was the nation’s last surviving Liberty Tree. It was so damaged by storms and decay it had to be cut down in 1999.

MARCH INTO BATTLE

The museum’s interactive exhibits let visitors get up close to weapons and involved in a key British victory on the road to capturing Philadelphia.

The Battlefield Theater turns tourists into soldiers for a few intense minutes. Visitors are gathered in groups of 25 and are taught how to muster like a company and march together into the theater, which soon transforms into the Brandywine Battlefield, site of one of the most significant skirmishes of the Philadelphia campaign on Sept. 11, 1777.

Washington’s loss there was a key step in the British capture of Philadelphia. The floor shakes with explosions, the air fills with smoke and the smell of gunpowder and visitors are face to face with the British infantry.

The Arms of Independence section has a vast display of weapons used during the war, and includes a fife and drum. A digital interactive display that filmed each weapon in high-definition video lets visitors virtually handle each weapon — or instrument — and learn more about their uses, owners and makers.

CHILDREN OF WAR

A trio of displays highlights the experiences of children during the war.

In a corner of a glass case that could easily be missed are four small toys worth examining. They were excavated from British Revolutionary War campsites around New York City. There’s a small, white stoneware lamb, a tiny pewter goose and a little pewter toy broom and platter.

In a separate glass case hangs a set of tiny wrist shackles likely forged to restrain a child. At the start of the American Revolution, slavery was legal in every colony. That meant all children of enslaved black mothers were also slaves.

Descendants of a Massachusetts soldier donated a newborn’s shoes that were made from a British red coat that was brought back at the end of the war and preserved through generations. Written accounts tell the story of the young man, who went off to war in 1775, rose to the position of sergeant in 1783, lost his brother in an attack that ended in a mass grave burial, and returned home to marry and have a child.

About 10 percent of British soldiers who arrived in New York in 1776 had their wives and children with them.

If You Go…

MUSEUM OF THE AMERICAN REVOLUTION: 101 S. Third St., Philadelphia; www.amrevmuseum.org. Daily, 10 a.m.-5 p.m. Adults, $19; children 6-18, $12. Opens April 19.

KRISTEN DE GROOT, Associated Press