ALEXANDRIA Va.

In a city well known for famous slaveholders George Washington and Robert E. Lee, an office building planned on the site of a notorious slave pen will provide its first monument to slaves.

The five-story building in Old Town Alexandria will be named Edmonson Plaza, after Emily and Mary Edmonson, two Maryland teenagers who were held in a pen on that site in 1848 after they and 75 others attempted to escape slavery on a boat.

The girls, ages 13 and 15, fled captivity to avoid being sold to brothel owners in New Orleans. The schooner was soon caught, but the girls were ultimately purchased out of slavery.

After hearing their story, Harriet Beecher Stowe wrote "Uncle Tom's Cabin," a novel that helped shift U.S. attitudes toward slavery.

Washington, D.C.-based development firm Carr Properties proposed creating a memorial and has agreed to pay for it. The firm, city planners and civil-rights activists are conferring about what the memorial should look like. A plan will be detailed this week.

"The site is seminal for Alexandria history, and we shouldn't forget the terrible hardships that people endured," said Michael Miller, a research historian with the Office of Historic Alexandria. "I hope it's well-marked, with accurate historical information."

Alexandria once was a major slave-trading center a place where slaves from Maryland, Virginia and the District of Columbia were held in pens and transported for shipment to cotton-growing farmers in the Deep South.

Jonathan Rak, a zoning lawyer for Carr Properties, said the company decided to emphasize the site's history instead of ignoring it, particularly once officials realized that many people were unfamiliar with the Edmonsons' story.

"People were aware it was a slave jail, but most people were unaware of the connection to the Edmonson sisters and 'Uncle Tom's Cabin,'" Rak said.

The book was published in 1851 and is a fictional account of the lives and travails of Eliza and her baby, Uncle Tom, Topsy, Eva and cruel-hearted slave owner Simon Legree. Abolitionists said it underscored the barbarity of the slave trade. But some Southerners said Stowe was exaggerating and that most slaves were treated kindly.