Palm House

Belfast's Botanic Gardens were founded in 1828 by the Belfast Botanic and Horticultural Society, which a decade later set about building a large glasshouse, ahead of both Glasnevin in Dublin and Kew. The foundation stone was laid on 22 June 1839 by the Marquess of Donegall, to designs by the architect Charles Lanyon.

The two wings were built by the Dublin ironmaster Richard Turner and completed in 1840 at a cost of £1,400. Turner went on to build the glasshouses at Glasnevin and, between 1844 and 1848, the Palm House at Kew. The central dome that completed Lanyon's scheme was added only in 1852, by a different firm, Young of Edinburgh. Lanyon had raised its height above the original plans so that taller plants could be grown.

The glasshouse quickly made a name for itself: an 1861 guide claimed the garden's conservatories held some of the rarest specimens in any collection in the United Kingdom. A symbol of Belfast's Victorian industrial prosperity, it is now listed Grade A, the highest category of protection in Northern Ireland.

The Palm House is among the oldest surviving curvilinear iron-and-glass glasshouses, combining cast and wrought iron. It is made up of three parts: two low wings flanking an elliptical central dome. According to the Victorian Web, each wing is 65 feet long, 20 feet high and 20 feet wide. The dome's height is given as 40 feet by Atlas Obscura, 46 by the Victorian Web and 49 by the Friends of Belfast Botanic Gardens, or roughly 12 to 15 metres.

Each section has its own climate: the west wing is a cool, temperate house, the dome holds subtropical plants and the east wing is a tropical stove house. Original features survive, including the external iron trim, ornamental grates and staging.

Every year its 8,000 or so panes are whitewashed from the top of the dome downwards, using scaffolding and pressure sprayers, to stop the morning sun from scorching the foliage; the coating comes off around September.

The central dome keeps the building's original purpose alive with a historic palm collection and a Norfolk Island pine (Araucaria heterophylla). The tropical wing holds bird of paradise, frangipani, bromeliads, orchids and peace lilies, while the temperate wing, used for seasonal displays, features geraniums, fuchsias, begonias and the fragrant Rhododendron fragrantissimum.

Two Australian plants stand out in the glasshouse's recent history: a Xanthorrhoea around 400 years old, and a globe spear lily (Doryanthes) whose 11-metre flower spike finally bloomed in March 2005 after a 23-year wait.

The Palm House stands in Botanic Gardens, a five-hectare public park off Botanic Avenue, next to Queen's University; the University Road entrance is the closest. Admission is free.

The glasshouse itself takes around half an hour and pairs well with the neighbouring Tropical Ravine, a walk through tropical vegetation laid out in 1889 in a glass-roofed brick building by the gardener Charles McKimm. Through the sunnier months the whitewashed dome gives the building a distinctive look; it regains its transparency around September.