On Sunday 20th June 2004 the Twentieth Century Society publishes a list of very recent buildings it feels are threatened in some way. Up there along with airports, cinemas, the Royal Shakespeare Theatre in Stratford and Battersea Power Station is Huddersfield Market Hall, the only building in Yorkshire to make the list.

Kirklees Council is considering seven different options to redevelop the area around the town's library and is asking for comments from the public. Some of these options involve demolishing the Market Hall. An architect and a local historian, both Huddersfield residents, preset the case for and against keeping the Market Hall.

Huddersfield is known for its Victorian architecture. It is less known for its Georgian buildings, and its 20th century heritage doesn't get a second glance. But the late 1960s saw the construction of perhaps the finest building in town.

Although Nicolas Pevsner describes Huddersfield's grade one-listed railway station as having "the best neoclassical station façade in Europe", as a Huddersfield resident - and an architect - I believe the Queensgate Market Hall is at least as significant.

A spectacular combination of architecture, engineering and art, it was opened on the 6th April 1970. It replaced an older, much-loved market hall, and largely because of this, I suspect, it has never achieved the recognition it deserves. The building celebrates the ancient roots of commerce: local people coming together to buy and sell things at reasonable prices. This is perhaps the very first reason we have towns and cities and here, the market hall creates a truly magnificent setting for this delightful, egalitarian activity.

However, the bustle of the market so demands the attention that it is easy to miss its main architectural attraction: the serene, airy 'forest canopy' that floats overhead.

'The roof acts as 'treetops' above the shoppers

The main hall is a composition of 'trees' or 'mushrooms'. Each tree has a concrete canopy, or shell, supported by a single central column, which forms the 'trunk' of the tree. The concrete was poured into timber 'moulds' or 'formwork' in situ, and allowed to set, to form the canopies. Each canopy is a kind of twisted rectangle measuring 56 feet long by 31 feet wide. The shape of the shell is defined as an asymmetric rectangular 'hyperbolic paraboloid', or 'hypar' for short. There are 21 trees in all, twenty of which form a four by five grid, or 'forest'. The shell canopies are set at different levels to each other, and vertical strips of glazing cover the gaps between the edges of the shells, effortlessly forming simple, high-level strip windows.

The natural light from this glazing spills across the underside of the shells, revealing both the texture left by the formwork, and the spectacular curved, twisted shape of the canopies. The shells, in turn, diffuse the light and eliminate glare. The concrete is of excellent quality, and has weathered very well. Standing in the market hall is like being in a cathedral. It is breathtaking.

These amazing structures are completely free-standing. They receive no bracing from each other. Although there appears to be some steel linking some of the corners of the 'treetops' together, a closer look reveals that this is just electrical ducting. I don't think concrete hypar shells have been used in this way anywhere else. They are very likely to be unique.

What is even more astonishing is the economy of these special shell structures. They cantilever out from their column a staggering nine metres - a normal beam in concrete or steel, cantilevering out as far as this might be expected to be at least a metre deep. These shells are as little as 75 millimetres thick!

Both natural and mechanical ventilation have been cleverly integrated into the strip windows.The only interruptions to the surfaces of the shells - the light fittings and fans - are both, I believe, recent additions.

The architects also integrated significant and vast works of art, both inside the scheme and out. Inside the market hall there is a spectacular welded steel mural, running most of the length of one of the interior faces of the wall, some 50 metres long, with scenes of life, commerce, bustle and movement. Outside, on the main façade to Queensgate (the Huddersfield ring road) there is a procession of nine very large, deeply carved and textured terracotta panels, also on the theme of 'movement'. These panels each measure over 5 metres square.

Both works, though different in character, are by Stratford-on-Avon artist Fritz Steller of the Square One studio in Warwickshire. The form and texture of these terracotta panels, and the free edges of the concrete shells, apparently flying over head, offer the ring road a façade of truly dramatic composition. The view of this façade, as you drive around the town, is possibly even more exciting at night, when the undersides of the shells are floodlit.

Detail from themural inside the market reflecting life, comerce and movement

Seymour Harris, the architects, obviously worked very closely with the structural engineers, Leonard and Partners, and Fritz Steller, to produce such a well integrated design. Sir Alfred McAlpine, the contractor, executed the design with considerable skill.

This building is now 34-years-old. It has weathered extremely well. Of course, it needs some care and maintenance. Yes, we must consider the needs of today's users of the building. But this is no reason to destroy such a work of art. It is a robust structure, very flexible to change. Let's give it the TLC it deserves. We could, if Huddersfield really wants a new market building, rehouse the market elsewhere and find a new and different use for the hall. Perhaps a glorious space for a gallery or exhibition? Or a light, airy covered street or square like the hugely successful Victoria Quarter in Leeds?

I don't wish to stand in the way of progress. By all means let's move forward with new and exciting cultural and retail buildings for Huddersfield. But if we are going to have landmark architecture, let's start by recognising the landmarks we already have.

It is an unlovely building. Very plain in appearance, architecturaly unexciting. I am not fond of elderly, grubby and greying concrete and its once-so-trendy black glass, initially tiny, is now dull and shabby. Its lack of attractiveness is, for me, emphasised by my memories of our glorious old Market Hall, and of the buildings which formerly occupied this site including a wonderfully ornate police station and our quaint old fire station, not to mention all the elegant buildings of Ramsden Street.

Are the market entrances "dark" and uninviting?"

Venture inside one of the dark, uninviting entrance tunnels and you feel you are leaving the sun and light of day for a claustrophobic warren, a mindless maze of stalls. You simply cannot get from A to B without going via C - very frustrating if you are in a hurry! I should hate to be in there if fire broke out. In addition, the atmoshere is of a dark and dingy cavern. In summer it is umbearably hot and airless, in winter it is cold and cheerless. Low ceilings combine with a lack of natural light to make it the kind of place where you don't want to linger, especially when the place is packed and you can only pass along the narrow aisles with great difficulty.

"There are some great shops..."

Which is sad, because the one positive feature of the Market is that there are some great shops in there! There are terrific bargains to be had, the variety of the stalls is amazing, some of them sell goods that take your breath away. A great shopping centre and potential tourist attraction, if only...! If only, once in there, it was a comfortable shopping environment.

It's time the stallholders were given a better deal in a building which compliments and enhances the goods for sale, and entices people inside.