It was praised by David Evans for the "almost barbaric power of its great cubic projections and cantilevers brooding over the conifers of the botanic gardens like a mastodon".

In July 2005, a £17m refurbishment of the museum was announced, with grants from the Heritage Lottery Fund and the Department of Culture, Arts and Leisure (DCAL, usually pronounced as 'Dee-Kal').

[7] The redevelopment drew criticism from many significant figures in the architectural community and the Twentieth Century Society, especially for changes to the Brutalist character and dismantling of the spiral sequence of rooms in the Pym extension.

The museum has galleries covering the history of Northern Ireland from the earliest times to the very recent past, collections of art, mostly modern or ethnographic, historic and contemporary fashion and textiles, and also holds exhibitions.

Works by Peter Scott, Joseph Wolf, Eric Ennion, John Gerrard Keulemans, Roger Tory Peterson, Charles Tunnicliffe, Robert Gillmor and Archibald Thorburn are included.

Illustrated works held by the Zoology Department include British Entomology - being illustrations and descriptions of the genera of insects found in Great Britain and Ireland – a classic work of entomology by John Curtis and Niccolò Gualtieri's Index Testarum Conchyliorum, quae adservantur in Museo Nicolai Gualtieri 1742.

Little information about the Irish flora before 1830 is available, the oldest specimen in the Ulster Museum is an alga: Batrachospermum moniliforme (BEL: F41) collected in 1798 by John Templeton, other specimens of Batrachospermum, originally incorrectly identified as Thorea ramoissima were collected by John Templeton in 1815 from a "boghole" in County Donegal (BEL:F42 – F47).

The museum's policy is to collect clothing and accessories as an Applied Art, with an emphasis on acquiring pieces that are of high design quality and/or representative of significant changes in fashion history.

The collection includes eighteenth-century Spitalfields silk gowns, early 20th century Parisian couture, and contemporary international fashion .

Designers represented in the collection include Chanel, Dior, Alexander McQueen, John Galliano, Vivienne Westwood and JW Anderson.

The textiles collection includes pieces by important female Irish embroiders, such as the 'Lennox Quilt' of 1712 by Martha Lennox, and a bedcover by the renowned eighteenth-century letter-writer and artist, Mrs Mary Delany.

The Ulster Museum's original collection of costume and textiles was almost completely destroyed in a fire following the 1976 bombing of Malone House in Belfast in November 1976, during the Troubles.

[19] One of the earliest items of costume destroyed in the fire was a lady's jacket of around 1600 with well-preserved polychrome silk and silver thread embroidery.

The main criterion became to collect fashion and textiles as an Applied Art and that it "must reflect the tastes and cultural interests and aspirations of the time it was made".

This enabled the Ulster Museum, almost alone in Great Britain, to be able to compete with American and continental dealers on equal terms for items which were considered particularly appropriate to the collection.

Notable pieces in the collection include a cut velvet and metal thread suit worn by the 'Black Rod' of the Irish Houses of Parliament in 1751, a number of very fine women's outfits of mid 18th century Spitalfields silk.

Many important designers are represented, from Paul Poiret, Coco Chanel and Christian Dior to Alexander McQueen, John Galliano and Vivienne Westwood.