In January 1998, workers began a three-year, $9.4 million renovation of the
Washington Monument, still the largest freestanding stone structure in the
world. (Unlike the ancient Egyptian obelisks, which are solid pieces of
granite, the Washington Monument contains 36,000 separate blocks of stone.)
First, they gave the inside of the 80,000-ton obelisk a complete mechanical
overhaul: new air conditioning, heating systems, and elevators. They then
refinished the exterior, replacing windows and cleaning and reshaping stones so
that they were perfectly level. In those stones missing chunks, workmen added
"dutchmen," pieces of replacement marble, rather than simply patching them. All
of these changes were particularly difficult, since only 12 to 16 people could
work at the project at once, due to the weight limitations of the 37 miles of
aluminum scaffolding wrapped around the monument (along with a blue mesh sleeve
to catch any falling tools or tool-users).
Another challenge was installing a new lightning-protection system. Originally,
the lightning-deterrent tip was a chunk of aluminum, which, at the time of its
installation, was the most expensive piece of aluminum in the world due to its
massive size. Workers replaced it with a tip comprised of platinum-tipped,
gold-plated rods, which were built so that little service would ever be
required, due to the difficulty of servicing the exposed and extremely lofty
tip of the 550-foot monument.
Principal sources: "Renovating Washington's Monument, Designer-style,"
SmithsonianMagazine, June 1999, and the U.S. National Park