Friedrich Herrmann Rötschke, who lived from 1805 to 1893 and is described in the records as the knight of the local town, laid out roughly eighty hectares of parkland in the nineteenth century, reportedly over the grounds of a former feudal estate. What he made was a landscaped park rather than a formal garden: winding water, planted islands, sightlines that reveal things gradually. The azaleas and rhododendrons that give the park its name came later to dominate it, and they set the calendar. Late spring turns the understorey into banks of pink, magenta and white beneath old pines and oaks. The park holds more than the famous arch, too, including the Kavalierhaus, a smaller bridge in an Asian idiom crossing to the island pond, and a Hercules figure standing among the shrubs.

Nothing about the Rakotzbrücke's material is local accident. The columns are artificially formed basalt, selected and brought in from distant quarries, then set to imitate the natural hexagonal jointing that basalt develops when a lava flow cools slowly. Thin rock spires rise from the water at either end of the span, arranged so they read as an outcrop the bridge happens to have been built onto rather than as ornament shipped in by cart. The stonework mixes that imported basalt with rougher local fieldstone. Seen from a few metres away in flat light, the whole assembly looks like something the ground did on its own. That was the intention, and it is the reason photographs of the bridge circulate so widely without any explanation attached: nothing in the picture announces that it was designed.

You will not be crossing. The bridge was renovated in 2018 and 2019, and crossing has remained forbidden throughout, both for the safety of visitors and for the survival of the structure itself. A thin nineteenth-century arch of stacked basalt columns was never meant to carry a queue of people, and the surface that reads so beautifully from the bank is uneven and steep underfoot. The restriction is not a hardship. The circle only works from the shore anyway; standing on the bridge is the one position from which you cannot see the thing the bridge was built to do. After the Second World War the park was nationalized, and it has stayed free to enter ever since, with only a small charge for parking.

The park sits in the village of Kromlau, in the municipality of Gablenz, in Upper Lusatia at the far eastern edge of Saxony close to the Polish border. Those are the German names. In Upper Sorbian, the language of the Slavic minority indigenous to this region, the village is Kromola and the municipality is Jabłońc, and the park is the Acalejowy a Rododendronowy Park Kromola. Gablenz lies inside the officially recognized Sorbian settlement area, where road signs carry both names by law. The municipal coat of arms puts the point plainly: it shows the Rakotz Bridge alongside apples, jabłučina or jabłoń in Sorbian, a pun on the village name that only works in the older language.

The circle is conditional. It needs windless air, a pond unruffled by rain or ducks, and light coming from an angle that does not scatter off the surface. Photographers arrive early for exactly this reason, and plenty of visitors see only a handsome stone arch over dark water and wonder what the fuss is about. Come back an hour later and the pond has gone glassy and the illusion snaps shut, the reflected half of the arch fitting the real one so exactly that the join disappears. It is a trick of engineering, patience and weather working together, staged in a quiet park in a corner of Germany that most maps treat as an afterthought.