Most, but not all.
"If you're walking with me," Manning says, "you have no choice but to know what happened here."
THE FORGOTTEN CRASH: History lost and relived
On a fog-shrouded evening on the penultimate day of 1906, a dead-heading train roared down this stretch of tracks near Washington's Catholic University, coming upon a slower passenger train heading the same direction on the same track. There was no time to stop.
Railroad workers have an antiseptic -- but descriptive -- word for what happened next: Telescoping.
The massive steel engine of the speeding train plowed through the flimsy wooden passenger car of the slower train, killing and dismembering its occupants. It plowed through the next car as well, and the one after that. When the trains came to a stop, cinders and soot from the locomotive's fire box rained down on the splintered wooden planks, clothing, Christmas gifts and human remains. Fifty-three people died, and more than 70 were injured.
Today, the "Terra Cotta" crash is all but lost to history. Every day, thousands pass the site, where there isn't even a hint of the horror that happened.
But Richard Schaffer, a D.C. firefighter who spent 10 years researching the crash, says Terra Cotta nonetheless changed railroading. It hastened the conversion of passenger cars from wood to steel and led to improvements in railroad signaling. That happened, he says, because the crash happened on "the route to Congress."
There's a saying, sometimes attributed to Mark Twain: "History doesn't repeat itself, but it does rhyme."
History rhymed in June 2009 -- nearly 103 years later -- when a D.C. Metro subway train plowed into another subway train. The cars telescoped, killing nine and injuring dozens.
"The irony was it was practically the same location and practically all the same problems, human error, signaling problems, construction quality of the trains," Schaffer said.
Both wrecks deserve to be remembered.
"If you forget what's happened before you," Schaffer says, "you don't have a foundation to live upon."
CONGRESSIONAL CEMETERY: The last hurrah
Can there be any doubt what happens here when the sun goes down?
Can there be any doubt that, when the gates close and the last visitor leaves this historic burial ground, band leader John Philip Sousa reaches for his baton, Civil War photographer Mathew Brady tweaks his camera, and J. Edgar Hoover tries to keep the whole mess under control?
This is Congressional Cemetery, where Washington's political and social establishment rests in eternal peace. In the 1800s, its heyday, this was the site of grand funeral processions. Tens of thousands of Washingtonians would gather to watch soldiers carry fallen leaders down a slate path to graves or crypts.
"I'm sure there are quite a few secrets buried here," says Abby Johnson.
Abby and her husband Ronald, professors of literature and history respectively at Georgetown University, take me to the "Public Vault," a crypt the size of a one-car garage. Built in the 1830s, the vault was used to store the bodies of public officials until the ground thawed, or until they were moved to other locations.
You need a skeleton key, of course, to get inside.