Royal Palace

This building was never supposed to be a palace. When Jacob van Campen designed it in 1648, it was Amsterdam's city hall — the biggest, most extravagant municipal building in Europe, and contemporaries called it the Eighth Wonder of the World without a hint of irony. The message was clear: Amsterdam's merchant class had more money and more power than most kings, and they wanted everyone to know it.

The engineering alone was staggering. The entire structure sits on 13,659 wooden piles driven deep through Amsterdam's marshy soil into the sand layer below. Without those piles, the building would have sunk into the swamp like everything else. Construction ran from 1648 to 1665, and the Citizen's Hall inside — a cavernous marble room with the Eastern and Western hemispheres inlaid into the floor — was deliberately designed to make visitors feel small. The maps underfoot showed Amsterdam's global trading reach, from the East Indies to Brazil.

Then Napoleon's brother Louis showed up. When he became King of Holland in 1806, he commandeered the city hall as his royal residence. He complained the weigh house on the square blocked his view, so he had it demolished in 1808. He also left behind the largest collection of Empire furniture outside of France, which still fills the rooms today.

The building remains the official reception palace of King Willem-Alexander, though nobody actually lives here. It welcomes roughly 300,000 visitors a year, most of whom walk across those marble hemisphere floors without realizing they're standing on a 17th-century flex.