In 1884 New Yorkers stepped over a small aluminum pyramid on the floor of Tiffany’s so they could say they had stood above the top of the Washington Monument. Getting there took decades. Congress authorized an equestrian statue in 1783, but Jeffersonian Republicans resisted anything like a royal shrine. The private Washington National Monument Society, formed in 1833, picked Robert Mills’s 1845 design: a 600-foot obelisk rising from a colonnaded temple topped by Washington in a six-horse chariot. The site on the L’Enfant plan proved too marshy, so the monument moved almost 400 feet, and the cost forced the design down to a plain obelisk. Construction began July 4, 1848, and historians agree enslaved laborers likely quarried and hauled much of the stone.

In 1854 Pope Pius IX donated a stone from the Temple of Concord, and members of the anti-Catholic Know Nothing party stole it and reportedly dumped it in the Potomac. In 1855 they took over the society by packing a meeting with new paying members, Congress pulled $200,000, and work stalled. After the Civil War the monument stood as a 152-foot stump until 1879, when Army engineer Thomas Lincoln Casey tunneled under the base and widened the foundation two and a half times. That 20-year gap shows in the three shades of Maryland and Massachusetts marble on the shaft. Completed in 1884, it was briefly the tallest structure in the world, passing Cologne Cathedral until the Eiffel Tower.

• Why the aluminum capstone was precious in 1884, and how the Hall-Héroult process made the metal cheap two years later
• The Jefferson Pier, the small marker at the originally intended site
• The steam-powered materials hoist converted for passengers as crowds reached 55,000 visitors a month
• Geological tuberculosis: mortar leaching into white calcium deposits down the pre-war section
• Norman Mayer’s 1982 standoff and the 2011 earthquake that left over 150 cracks and a $15 million repair