Radiolab has posted an informative and entertaining essay entitled “How to Cross 5 International Borders in 1 Minute without Sweating.” It describes the intertwined municipalities of the Dutch town Baarle-Nassau and the Belgian town Baarle-Hertog. Here’s the evocative description by Robert Krulwich of Radiolab:
The hunky yellow bit labeled “H1″ (for Hartog) toward the bottom is mostly the Belgian town. But notice those little white bits inside the yellow — labeled “N1, N2, N3″ — those are little patches of the Dutch town (N for Nassau). The two towns are not geographically separate. Instead, they’re like M&M’s in a candy bowl. There are 22 distinct Belgian bits, and a dozen or so Dutch bits, and they are sprinkled together; so sometimes you’ve got bits of Belgium inside Dutch areas, and sometimes Dutch patches inside Belgian neighborhoods. They vary in size. The largest is 1.54 square kilometers, the smallest, an empty field, is 2,632 square meters.
Krulwich is correct to note that in the Middle Ages “Checkerboard maps were common.” One reason they were common was that feudalism had a different conception of sovereignty than the “modern” conception of sovereignty that became prevalent in the years following the Peace of Westphalia in 1648. Rather than strictly territorial, medieval sovereignty was in part relational, between lords and subjects as well as between and among varying levels of nobility. With an emphasis on personal loyalty and duty, the feudal conception of sovereignty was like a network of individuals with multiple linkages and relationships. Displaying such relationships as a territorial map with bold-line boundaries results in a crazy quilt that may actually obscure the complex interwoven relationships.
But the Westphalian emphasis on territorial sovereignty called for such bold-line maps. Areas that started as territorial patchworks were usually consolidated and rationalized. Krulwich continues:
But for some reason, writes Alastair Bonnet in his new book, Unruly Places, it didn’t [happen here]. During Napoleon’s time, villages were swept cleanly into one nation or another, the borders tidied up, but apparently — and no one can quite explain why — Baarle-Nassau and Baarle-Hertog escaped the broom. Maybe they were too small, too unimportant, but they made it through, their mosaic-ness intact, becoming, Bonnet says, a “living laboratory of medieval micro-borders.”
For more detail on the land grants, treaties, planning commissions, and other aspects of the history of these two towns, see this website.
This mosaic of sovereignty has led to some incredible results. In a 2008 post on Baarle-Hertog/ Baarle-Nassau, BLDGBLOG reported that:
Sarah Laitner, at the Financial Times, adds that “women are able to choose the nationality of their child depending on the location of the room in which they give birth.”
For more about the administration of Baarle-Hertog and Baarle-Nassau, see this .pdf.
The contested status of two specific plots created by these micro-borders led to a dispute before the International Court of Justice, Sovereignty over Certain Frontier Land (Belgium/ Netherlands). The ICJ found that the plots in question were under Belgian sovereignty.
While perhaps the most complex territorial enclave, the two Baarles are not the only examples; see the website European Small Exclaves. You can also see more about Swiss cheese sovereignties and cartographic discrepancies in this post I wrote a while back. (And the part about cartographic discrepencies should really be considered by that guy trying to found a Kingdom of North Sudan for his daughter…)