Which monumental obelisk is the tallest structure in washington

d. c.?

Washington Monument - Washington D. C. The monument, made of marble, granite, and sandstone, is both the world's tallest stone structure and the world's tallest obelisk, standing 555 feet

Located almost due east of the Reflecting Pool and the Lincoln Memorial, the monument, made of marble, granite, and bluestone gneiss, is both the world's tallest stone structure and the world's tallest obelisk, standing 554 feet 7 11⁄32 inches (169.046 m) tall according to the National Geodetic Survey