Mini Washington Monument - Benchmark A

Historical landmark · Washington Monument Grounds

1

@atlasobscura

"Unknown to most passersby, there’s a 12-foot-tall replica of the Washington Monument under a manhole near the actual monument. Officially known as “Bench Mark A,” this underground oddity is actually a Geodetic Control Point that’s used by surveyors. It’s part of the network of a million control points across the country that helps the National Geodetic Survey (NGS) synchronize all of the government’s maps.   According to NGS modernization manager Dru Smith, “Geodetic control points provide starting points for any map or measurement. It has to be more accurate than any measurement you do on top of it, so we pick things that tend to be extremely stable.” Usually that means metal caps or rods that are driven down into the ground, but this quirky control point mirrors the form of its next-door neighbor. “All the surveys we’ve done, going back to the early 1900s, have used it,” says Smith. Most recently, it was used in the aftermath of the 2011 Washington earthquake. Measurements over the past century have shown that the marshy soil below Washington Monument has risen 6.2 centimeters, at an average rate of 0.5 millimeters per year. The mini monument was placed in the 1880s as a part of a trans-continental leveling program. The ground level here was much lower at that time, with large parts of the Washington Monument foundation still visible above ground (see fourth image above). The mini monument was above ground for a time, before being encased in a brick chimney and buried. Outside of surveying circles, it’s been largely forgotten." - ATLAS_OBSCURA

6 Secrets of the Washington Monument
NOAA's National Geodetic Survey (Public Domain)

2 15th St NW, Washington, DC 20024 Get directions

nps.gov

1 Postcard

See full details

More Places For You

Supra

Georgian restaurant · Shaw

Indulge in delicious Georgian khachapuri, vibrant wines, and playful cocktails amidst folk art in this rustic-mod hub for a truly charming experience.

16 Postcards

Bodega Taqueria y Tequila Foggy Bottom

Mexican restaurant · Foggy Bottom

Bodega Taqueria y Tequila brings a vibrant Miami vibe to Foggy Bottom, offering killer tacos, creative cocktails, and a buzzing speakeasy experience.

5 Postcards

Kirwan’s on the Wharf

Irish pub · Waterfront

This waterside watering hole's imported Irish decor stages refined pub fare, beer, whiskey & music.

5 Postcards

Cork Wine Bar and Market

Wine bar · U Street

A charming wine bar featuring New American small plates upstairs and a buzzing market bistro below, perfect for intimate sips and bites.

17 Postcards

Mr. Yogato

Frozen yogurt shop · Dupont Circle

This quirky fro-yo haven serves up delicious original and tangy flavors with fresh toppings, plus trivia fun and games for discounts.

4 Postcards

Hook & Reel Cajun Seafood & Bar

Seafood restaurant · Fort Lincoln

Welcome to a laid-back seafood haven where you can dive into signature boils packed with fresh crab and shellfish, all while enjoying good vibes and happy hour specials.

1 Postcard

Albi

Middle Eastern restaurant · Near Southeast

Discover a vibrant Middle Eastern hotspot serving up incredible hummus and innovative dishes, paired with unique cocktails in a relaxed atmosphere.

57 Postcards

Via Sophia

Italian restaurant · Downtown

Nestled within the Hamilton Hotel, this chic osteria serves up refined Italian dishes and wood-fired Neapolitan pizza in a stylish, modern setting.

12 Postcards

Lucky Buns at Union Market

Restaurant · Capital City Market

Lucky Buns at Union Market serves up juicy double patty burgers and crispy chicken sandwiches, all while you soak in the vibrant food hall atmosphere.

3 Postcards

The Crown & Crow

Bar · Logan Circle

Inspired by Victorian pubs, this expansive, lower-level watering hole features a 19th-century bar.

4 Postcards