The just-ended Black History Month brought volumes of hidden history out from Arlington’s shadows. I never cease to be astonished at how much neighborhood lore I missed while growing up here.

On Feb. 26, a crowd of 150 gathered for the ceremonial unveiling of the new marker for the “Hall’s Hill Wall,” at North 17th and Culpeper streets. Their podium, folding chairs and refreshments table were arrayed in front of an unprepossessing seven-foot cinderblock barrier. County and school board members and preservation officials joined with the Halls Hill/High View Park Historic Preservation Coalition to admire the metallic sign just installed beside the remnant of a once-longer racial divide.

The easy-to-miss structure dates to the 1930s, when the white subdivision of Woodlawn Village erected it to avoid mingling with African Americans. In the late 1950s, black children removed a chunk to clear access to a creek, and by 1966, with desegregation clearly the future’s wave, most of the rest came down, the sign explains.

“A wall can’t keep us from your love,” went the prayer led by a clergywoman, followed by recollections from decades-long residents of Hall’s Hill who grew up traveling to segregated schools back when George Mason Drive was called Frederick Street. “Hall’s Hill for 150 years was a community where everyone knew everyone,” said emcee Portia Haskins. “We helped raise each other’s children.”

“When I moved to Arlington in the 1980s, I didn’t know anything about this,” said County Manager Mark Schwartz. “I was stunned, but in a way I’m glad there’s a remnant—what is past is prologue.”

For lots of cultural and economic reasons, many black enclaves in Arlington have come and gone outside the consciousness of mainstream whites. You can read about them in the recently updated “Guide to the African American Heritage of Arlington County, Virginia,” by John Liebertz of the county planning staff.

Several were recalled vividly by Dr. Alfred Taylor, educator and historian of the Nauck neighborhood, who spoke Feb. 9 at the Woman’s Club of Arlington. Besides Hall’s Hill, there are numerous South Arlington offshoots of Freedman’s Village, the 1870s community of free blacks in what is now Arlington Cemetery. The mainstay was Nauck (named for German landowner John Nauck) but also called Green Valley (named for its beauty by another white developer).

South Arlington also brought East Arlington and Queen City near the Pentagon, and Johnson Hill (Walter Reed Drive) and Penrose (also called Hatfield) off Columbia Pike. In Ballston, the African-American Rev. Galloway sold the land that became Parkington for $85,000 in 1950, Taylor said. There was a black community on Moore Street in Rosslyn.

Among those that have vanished in recent decades: The Dunbar and George Washington Carver homes, both projects supported by mutual home assistance societies, and the Arna Valley apartments off South Glebe Road.

Perhaps the least known was an enclave between North Powhatan and Quantico Streets at railroad tracks near today’s I-66, I was told by Bruce Harmon, who grew up in the white section of Overlee Knolls in the 1950s. “The boys I ran with there were all unreconstructed rebels, and they called the houses the n***er shacks,” he wrote to me recently. “They told me they sometimes threw rocks at them. I never knew what happened to those people when the government took their homes for the highway.”

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Note to you Arlingtonians who’re renting out spare rooms under Airbnb and the like: get ready to shell out a fee.

County Manager Mark Schwartz’s Feb. 22 budget proposal for fiscal 2018 announced an annual $60 fee for a new accessory homestay permit.

No word on whether the budget — due to be voted on in April — would also apply, for the first time, the transient occupancy tax long paid by hotels to the county’s burgeoning roster of Airbnb hosts.