Sale:: Why does the Capitol have tiny doors?

Monday, February 2, 2026

Why does the Capitol have tiny doors?


	February 2, 2026

Original photo via Architect of the Capitol

The U.S. Capitol has strange tiny doors.

While they're quite minuscule and often painted to blend in with their surroundings, you may notice several strange, tiny doors with decorative trim should you ever wander the halls of the U.S. Capitol. Those doors appear to be more appropriately sized for small creatures than for any congressperson, as they measure roughly 30 inches tall. However, they were never meant to be used as entryways or exits; rather, they concealed hidden water sources that once aided in fire prevention and cleaning.

Behind each mini door is a pipe and spout that used to carry fresh water directly from the Washington Aqueduct into the Capitol. The system was implemented in the wake of a devastating fire on Christmas Eve in 1851, which destroyed 35,000 volumes preserved by the Library of Congress. An investigation showed the fire could've been extinguished with ease had there been an available water supply nearby, and engineer Montgomery C. Meigs was subsequently tasked with developing a solution.

Meigs installed these on-demand water sources throughout the Capitol, concealing them behind miniature doors that could be easily opened in the event of future fires. Not only did the water aid in fire prevention, but janitorial crews also used those hidden faucets to fill their pails for cleaning purposes. Today, the doors and water sources no longer serve an essential purpose, as the Capitol is outfitted with modern fire suppression systems. But those doors remain an eye-catching relic of yesteryear and are a popular talking point among visitors.

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		Numbers Don't Lie

Approximate weight (in tons) of the U.S. Capitol dome

4,500

People who have served as architect of the Capitol

Total square footage of the U.S. Capitol

175,170

Windows in the U.S. Capitol

658

The U.S. Capitol used to have a smaller green dome.

Although the U.S. Capitol opened for business in 1800, its original dome wasn't finished until 1824. That dome was smaller than the current one, rising to 140 feet above the rotunda, compared to 180 feet today. It was also built from wood and covered with copper, giving the dome a green color far different from its now-familiar white hue. The wood material, however, posed a fire hazard and necessitated frequent repairs. There were aesthetic issues as well, as large-scale expansions to the rest of the Capitol made its dome appear disproportionately small. A bigger and more durable replacement was approved in March 1855, with construction beginning the following year and lasting until January 1866.