Days 23 and 24. Nyboder.

As an American, it's always impressive to see buildings that are older than the US itself. Europe does a great job keeping its castles, churches, forts, museums and the like in shape for generations to enjoy. The centuries-old buildings that impress me the most, however, are the residential ones. That countless families have walked up and down the same steps, slept in the same bedrooms and peered out the same windows for hundreds of years -- without the wealth of the state for upkeep -- is a remarkable thing.

Smack dab in the middle of Copenhagen, between Rosenborg Castle and Kastellet, sits a collection of identical row houses called Nyboder. The distinct yellow hue of Nyboder has been copied on homes across Denmark, and today the row houses stand in stark contrast to the ornate six-story buildings surrounding them. Construction began by royal decree in 1631 to accommodate military families, but most of the homes standing today were built just before the American Revolution in the mid to late 1700s.