Garten der Schmetterlinge (Butterfly Garden), Sayn Castle

The butterfly garden owes its setting to Sayn Castle, at the foot of the hill crowned by Burg Sayn. The cultural-heritage platform KuLaDig reports that a medieval Burghaus of the 14th century passed by marriage to the Boos von Waldeck barons, who rebuilt it as a Baroque manor in the 18th century. In 1848 the Sayn-Wittgenstein-Sayn family, returning from Russia, bought the estate. The architect Alphonse François Joseph Girard turned it into a neo-Gothic castle between 1848 and 1851, and the landscape park was planned by the architect Carl Friedrich Thelemann (1811-1889). Heavily damaged shortly before the end of the Second World War, the castle kept only its outer walls; its reconstruction lasted from 1995 to 2000.

It is in this park that Gabriela, Princess of Sayn-Wittgenstein-Sayn, opened the butterfly garden in 1987, housed in two glass pavilions. The official site presents it as a nature experience tied to raising awareness of the protection of native butterflies; it has operated for more than three decades and is recognised as an out-of-school learning venue. A neighbouring pavilion hosts temporary exhibitions.

The castle and the English-style park, with its late-Baroque garden house, are among the protected cultural monuments of the Mayen-Koblenz district.

The garden is described either as two "Glashallen" (glass halls) or as two "Glaspavillons" (glass pavilions): glazed volumes sheltering tropical vegetation, under which butterflies fly above visitors' heads. The collaborative OpenStreetMap survey distinguishes three building parts with gabled glass roofs on the footprint. According to the official FAQ, the climate is held at about 24 °C with 70 to 80 % humidity.

The route includes paths, a footbridge, benches and a waterfall. A climate lock (Klimaschleuse) leads to the caterpillar house, the Raupenhaus, a separate structure where eggs, caterpillars and pupae can be seen and where some species are bred with their food plants. Terrariums house reptiles, amphibians and insects. Native butterflies are not kept inside: a nature trail around the glasshouse offers nectar plants and host plants for local species.

Orchids, palms, banana plants and hibiscus make up the planting of the two halls. The official site reports more than fifty butterfly species over a season. It names the Atlas moth from China, with a wingspan of about 30 cm, the blue morpho from Brazil, a passion-vine butterfly (Passionsfalter), a glasswing (Glasflügelfalter), Cethosia cyane and the Himmelsfalter and Schokoladenfalter. During the season the garden receives 200 to 300 pupae each week from breeders in tropical regions, including Costa Rica, Kenya, Malaysia and the Philippines, and breeds some species itself in the caterpillar house.

Other animals share the space: families of dwarf quails, tortoises, tropical finches and Japanese koi, as well as, in the terrariums, a blue tree frog and various insects, among them stick insects and katydids. Every year from mid-October the event "Blaue Wunder von Sayn" (the blue wonders of Sayn) fills the garden with blue morphos until the end of the season.

The garden stands in the Fürstlicher Schlosspark, next to the castle, which houses a museum. The visit combines naturally with a walk through the park, with Burg Sayn above the site and with the nearby Sayner Hütte: KuLaDig describes the group formed by the castle, its park, the castle ruin and the ironworks as well worth seeing. The season runs from March to early November. Native butterflies can be seen along the outdoor trail from March to October depending on the weather, the brimstone in early spring and the swallowtail later on. The end of the season is marked by the blue morpho event from mid-October. Dogs are not admitted to the garden.