LOBITH, NEAR where the river Rhine enters the Netherlands, has been a border town ever since northern Europe has had borders. Buried nearby lie the remains of a Roman camp that in the first century AD guarded the limes, the fortified line protecting the empire from Germanic tribes. In 1672 Louis XIV of France crossed the Rhine here with an invading army, launching the “year of disaster” that ended the Dutch Golden Age. Today the Dutch-German border runs along a quiet street of villas east of town. Barges ply the river; on the dyke-top cycling path, you notice that you have switched countries only when the signs acquire umlauts.