Tropenhaus of the Haus des Meeres (Aqua Terra Zoo)

The Haus des Meeres occupies one of the anti-aircraft towers (Flaktürme) raised in Vienna during the Second World War, the one in the Esterházypark in the 6th district (Mariahilf). The association that runs it was founded on 26 November 1957 expressly to create this vivarium, which opened the same year; it became the owner of the tower in 2013, the structure having lost its listed status in 2003.

The Tropenhaus, attached to the west face, opened to the public on 7 September 2000 after a year of construction. According to Wikipedia, this extension raised annual attendance to 180,000 visitors. Growth continued: in June 2018 work began on a glazed extension with 3,000 m² of usable space, funded by the association and costed at ten million euros, which was completed in 2020. In the year before that project the Haus des Meeres had received some 630,000 visitors.

In 2023, after more than twenty years of intensive use, the Tropenhaus underwent a complete renovation, demolition included, carried out over eight months. The visitor route inside was redesigned from end to end.

The Tropenhaus is a glass-walled structure akin to a winter garden, grafted onto the west face of the concrete tower, which stands about 47 metres tall according to OpenStreetMap. A Viennese outings guide notes that, like the Krokipark, it is a glazed extension set 20 metres above the ground; the collaborative map records it as a projecting volume under a single-pitch glass roof.

The 2023 renovation transformed circulation inside: walkways and ramps now hang from the structure, which lightens the space, and gradients of no more than 6 % ensure step-free access. Wood-composite decking was chosen because it resists moisture, is slip-resistant and does not splinter.

The 2020 extension, placed in front of the entrance facade, continues this approach of glass envelopes attached to the bunker: it added 3,000 m² of usable space, two lifts including a panoramic one, an enclosed viewing terrace and an enlarged café on the 11th floor. A photovoltaic array of 202 modules was installed as part of the work.

The Tropenhaus is designed as a shared habitat with no barriers between animals and visitors: birds fly freely, white-tufted marmosets roam at liberty, and fruit bats and tortoises live there too, in a tropical climate. The neighbouring Krokipark, another glazed extension, follows the same principle of birds in flight and monkeys moving freely.

The extension completed in 2020 houses a Madagascar zone, with indoor and outdoor sections, home to ring-tailed lemurs and other lemurs, a narrow-striped mongoose, a giant tortoise and three Komodo dragons. Altogether the Haus des Meeres shows more than 10,000 animals over more than 5,000 m².

The Haus des Meeres stands in the Esterházypark in the Mariahilf district, beside Fritz-Grünbaum-Platz. The Tropenhaus forms part of the tower's vertical route, followed floor by floor; its warmth makes it a pleasant stop in winter, and a visit to the whole building combines easily with a walk in the park.

The visit can end at the top, with a terrace on the 9th floor and a panoramic café on the 11th. Outside, the face of the tower carries a climbing wall run by the Austrian Alpine Club.