https://phys.org/news/2018-09-capital-levee-hurricane-florence.html

Three meters (ten feet) high in places, the stone wall seems to blend into the landscape just north of the Tidal Basin, the picturesque reservoir surrounded by monuments near the Potomac River.

But its role is suddenly a hot topic as city leaders declared a state of emergency and waters on the swollen Potomac surged past flood stage this week following recent heavy rains.