Before this summer's train fire, not many people in Baltimore knew the 106-year-old Howard Street Tunnel had been underfoot all this time, let alone that it has a spot on the prestigious National Register of Historic Places.
As it turns out, the U.S. Park Service's idea of what is significant does not stop at elegant landmarks such as City Hall and creaky old mansions where somebody famous has lived.
The tunnel, known for its innovative engineering, is just one of several out-of-the-ordinary entries. The Baltimore sites on the National Register include an unusual iron-faced burial vault and a century-old bathhouse paid for by philanthropist Henry Walters so Pigtown residents could shower.
Travel beyond the city and the catalogue becomes odder still: a sunken World War II German submarine off St. Mary's County and a sweet-potato curing house on the Eastern Shore.
Some of the sites seem to be in good shape; others look their age.
"Really, there is all kinds of stuff," said Peter Kurtze of the Maryland Historical Trust, which oversees the state's list of about 1,300 properties. "That's one of the things that makes my job interesting."
The quirkier places, like all of the nearly 73,000 listed nationwide, are considered important to U.S. history, architecture, engineering, archaeology or culture.
Some are hidden from view. The U-1105 "Black Panther" sub in the Potomac River off Piney Point is visible only to fish and experienced divers who brave the murky waters. It was towed to Maryland after the war, sunk in a demolition test, raised and then sunk again.
A story lies behind the bricks and iron and steel of each place: There is Mathilda Weiskittel's deft cheating of death for about 70 years. And there's the gleeful pilgrimages of Walt Yanke and his buddies to Walters Bath No. 2 for their weekly 5-cent showers.
The National Register was formed in the 1960s as a way to keep urban renewal projects from ripping apart historic areas willy-nilly for highways and high-rises. Although a listing does not automatically keep the wrecking ball at bay, state and federal tax credits give owners an incentive to renovate rather than raze.
A spot on the list signifies that a place is worthy of protection, say those who have gone through the designation-seeking process.
"We were trying to preserve it," longtime Pigtown resident Leah Shifflett said, explaining why she led the charge to add the Walters bathhouse in the 1970s.
Work on the squat, one-story brick building began in 1901 and cost $27,000. When it opened in 1902, adults paid 3 cents for soap and towels; children, a penny. (Later, showers cost a nickel.) Downstairs, people could wash laundry in giant tubs for 2 1/2 cents an hour.
At the time, Baltimore lagged behind New York, Philadelphia and other cities in the movement to open public baths for residents. The need was evident: By the 1890s, National Register documents show, just one in 10 homes in Baltimore had bathtubs.
When no one else stepped forward, Henry Walters - the benefactor of the Walters Art Gallery - agreed to underwrite the cost of three bathhouses. Four were built, and No. 2, on present-day Washington Boulevard west of Camden Yards, is the only one still standing.
As a boy during the 1930s, Walt Yanke and his friends eagerly went in the door marked "Men." (Women used a separate entrance.) His house on Herkimer Street had a bathtub, but no shower, so "we thought it was really cool to go up there." A whistle blast at 3:20 told the boys to clear out because grimy men from the nearby Baltimore & Ohio Railroad yards would be along soon.
"Everybody from Pigtown used to go up there," said Yanke, 75. Everybody who was white, at least. Like many public institutions, the city's public baths were off-limits to blacks.
The bathhouse closed in 1959, and today the building houses the Washington Village-Pigtown Neighborhood Planning Council. The nonprofit group hopes to buy it from the city and use tax credits to help pay for an $800,000 remodeling.
While Walters baths were aiding in the cleanliness campaign, across the Chesapeake Bay the cultivation of sweet potatoes was taking off on the Eastern Shore.
The trouble was that sweet potatoes were prone to freezing in winter. About 1920, the Rounds family built a brick curing house on their Maple Leaf Farm, with foot-thick walls to help keep the temperature at 60 degrees.
The popularity of sweet potatoes faded, and in 1928 the Rounds family planted alfalfa hay and corn. They turned the potato house into a storage shed. Then a few years ago, it faced destruction because it lay in the path of the U.S. 50 bypass being built around Salisbury.
So T.J. and Fran Mumford stepped in and bought it, then moved it to their 20-acre farm in Hebron, where their 211-year-old house is surrounded by old farm buildings. The sweet potato house might become an office.