Thayatal

Thayatal, established in 2000, is the smallest of Austria's national parks — thirteen square kilometres you could walk across in a morning — and pound for pound perhaps its richest: one bank of one river valley, facing the Czech Národní park Podyjí of 1991 across the water, a single valley run as two parks. The Thaya leaves its farm plain here and cuts into the granite and gneiss of the Bohemian Massif in deep incised meanders, looping so hard around the Umlaufberg that the wooded spur is nearly an island. On its rock above the river sits Hardegg, Austria's smallest town: a castle, a church, and some eighty townspeople.

The valley owes its condition to the Cold War. For forty years the Czech bank was sealed border zone and the Austrian side a dead end nobody drove through, so the slopes kept their old oak and hornbeam sun-woods, their shadowed ravine forests, their knolls of dry grassland where feather grass and dwarf iris flower before the canopy closes. The Hardegg footbridge reopened in 1990, and walkers now cross mid-hike between countries; on the Czech side above Čížov a stretch of the actual Iron Curtain — wire, plough-strip and watchtower — is preserved as a warning. In 2007 a camera trap produced the sensation: a European wildcat, the first certain Austrian evidence in decades. The park has since become the country's wildcat headquarters, with a research programme and a walk-through enclosure at the Nationalparkhaus.

Over a thousand plant species crowd into this pocket of a park, black storks breed in the old woods and patrol the gorge, and otters fish the Thaya — density, not size, is the argument.

What's worth knowing before you go

Hardegg and the Nationalparkhaus at Merkersdorf are the bases; the nearest railway is Retz on the Vienna–Znojmo line, a wine town seventeen rolling kilometres away, covered by seasonal buses and a good cycle route. Cross to Čížov for the border relics, or make a two-park day of it and walk into Podyjí toward Znojmo. Spring brings the dry-grass flowers and the storks back; October colours the mixed woods; summer in the gorge is green, close and quiet.

The connoisseur's viewpoint is the Umlaufberg lookout — river on both sides of one wooded ridge, the meander read whole — best in low morning light.