Photo by Flickr user takomabibelot.

"Why do DC policemen attach sidecars to their motorcycles around this time?"

You’ve seen them around—the motorcycles with the little car attached to the side. While recreational bikers might use them as an attention getter, it serves a real purpose when utilized by the DC police force.

It helps provide extra stability during the winter months, according to Traci Hughes, the executive director of the public information office for the Metropolitan Police Department. She says that sidecars are typically attached from mid-October (after Columbus Day) until March 17.

How, why, and when did Meridian Hill Park become Malcom X Park? —Liz

While some might know it as Malcom X Park, the official name for the 12 acres of land between 15th and 16th streets and W and Euclid streets, Northwest, is Meridian Hill Park. It is so named because it’s located on the exact longitude of the original District of Columbia milestone marker. It became a park in 1936—22 years after construction began—according to the National Park Service.

So where did the Malcolm X nickname come from? A leader of the Black United Front began referring to the park in honor of the civil-rights leader on the one-year anniversary of the assassination of Martin Luther King Jr., says Simone Moffett, cultural-resource specialist for Rock Creek Park, the organization that deals with administrative issues for Meridian Hill. DC residents later voted for the name to be officially changed to Malcolm X. A bill to change the name was introduced to Congress in January 1970, says Moffett, but didn’t pass. Moffett says that because a presidential memorial is located in the park—in honor of 15th President James Buchanan—the name cannot be changed to represent another person.

Photo by Flickr user Bethany L. King 

Stephanie Caccomo asks: “What is the story behind the fish market barges on the Southwest waterfront? I think I’ve heard that they have been around for a while, but I’d love more info on their history.”

To get the facts on the fish market, we hunkered down with a stack of books and called in favors to two local historians. Read on to find out what we uncovered.

Photo of Thomas Circle in 1922 from Flickr user NCinDC 

“I’ve been told that the traffic circles, most with statues, in Washington were purposefully placed two cannon ranges apart so the city would be defensible from any point. Is this true, in whole or part?”—Kay Larson

As far as we can tell from our research, Kay, that wasn’t quite the case—though the traffic circles did have something to do with defending the city. While the circles throughout the District may now seem like a nuisance, they were originally meant to do more than frustrate drivers. Read on for the explanation.

Photo by Flickr user IntangibleArts 

“What the heck are those grass-covered rounded structures at the southeast corner of North Capitol street and Michigan Avenue? They look like something out of an old war movie.” —Sarah

Although they may look like a backdrop for Tom Hanks in Saving Private Ryan, the structures are actually abandoned sand washers that are part of the McMillan Reservoir’s sand-filtration system.

Alejandro Salinas asks: “What is Dupont Underground? Where is the entrance located? What’s the story behind it?”

The National Capital Trolley Museum staff and the Web helped us unravel the mystery of the Underground, while members of the Arts Coalition for Dupont Underground discussed its possible reincarnation with us. Read on for the scintillating answers!

Dupont Underground is an abandoned streetcar/trolley terminal and tunnel, which is located underneath Dupont Circle but above the Metrorail tracks. Several boarded-up entrances can be seen around the circle, including spots near PNC Bank and Krispy Kreme.

Photo by Flickr user dbking

“What’s the deal with the statues on horses? Is there any significance to them? I’ve heard that there’s some significance when their front leg is lifted.” - Liz Palmer

Several readers were wondering the same thing, Liz. With help from a reference librarian and good old-fashioned Internet digging, we’ve got it covered.