Washington Monument
This slender obelisk, 555 feet (166 meters) tall, was originally supposed to be surrounded by a colonnade with heroic statues. After more than 30 years of on-again, off-again construction plagued by low funding, the colonnade was abandoned well before the monument's dedication in 1885. At its center, 897 steps climb to an observation deck with beautiful views of the city. The steps are closed to the public except for ranger-guided tours, leaving an elevator as the sole path to the top.
Related site: National Park Service Washington Monument