Gallery of Modern Art, Glasgow

Stand for a moment in Royal Exchange Square and listen. Buskers play on Buchanan Street nearby. Footsteps echo off pale sandstone. Pigeons settle on the cornices. In front of you rises a temple of honey-coloured stone, with tall fluted columns and a deep shaded portico. It looks ancient and calm. Then your eye drifts down to the horseman out front... and you notice the orange traffic cone on his head. Welcome to the Gallery of Modern Art, which most Glaswegians simply call GoMA.

That contrast, between grand classical stone and cheeky street humour, is a good key to the whole building. This is a place where old wealth and new ideas sit side by side. The columns speak the language of ancient Greece and Rome. The art inside speaks the language of the present day. And the people of Glasgow have added their own commentary, quite literally, on top of a bronze duke.

The story begins in the late eighteenth century, in the age of the tobacco lords. These were Glasgow merchants who grew enormously rich from the transatlantic tobacco trade. That trade depended on plantations worked by enslaved people in the Americas. One of these merchants, William Cunninghame, built a fine townhouse on this spot in the 1770s. At its core, the gallery you see today is still that merchant's mansion.

This is the first surprise most visitors miss. The building does not tell its origins openly. The grand front came later. Wrapped inside the classical shell is a private home paid for by tobacco money. In recent years, Glasgow has started to speak more openly about how much of its eighteenth-century wealth came from slavery. Standing here, it is worth holding both truths at once — the elegance of the stone, and the human cost that paid for it.

After the merchant era, the house changed hands and changed purpose. For a time it served as a bank. Then, in the early nineteenth century, it was rebuilt as the Royal Exchange. This was a meeting place where merchants and traders gathered to read the news, check shipping reports and strike deals. The architect David Hamilton gave it the deep Corinthian portico you see now. Corinthian columns are the most decorative of the classical styles, with capitals carved like curling acanthus leaves.

The square around you grew up with the Exchange. Notice how the buildings on either side frame the gallery like the wings of a stage set. At the far end, a pair of archways lead back out toward Buchanan Street. The whole arrangement was planned so that you approach the Exchange head-on, as if walking toward a temple. Even the café tables and the pale paving stones play their part in that calm, symmetrical view.

Now, the duke. The bronze rider is the Duke of Wellington, the general who defeated Napoleon at Waterloo. The statue is the work of the Italian-born sculptor Carlo Marochetti, and it dates from the mid nineteenth century. It was meant to be a solemn tribute. For decades, though, Glaswegians have climbed up and placed a traffic cone on the duke's head. Nobody quite agrees on when the habit started. Locals tend to say it began sometime in the late twentieth century.

Here is the second surprise. The city authorities once proposed raising the plinth to stop people climbing it. The public response was loud and overwhelmingly against the plan, and it was dropped. The cone is now one of the most photographed sights in Glasgow. Many people see it as a small act of affection — a city refusing to take its monuments too seriously. Look closely and you may also see the cone replaced by a seasonal or protest version.

In the twentieth century, the building found yet another life as Stirling's Library, a public lending library. Then, in the 1990s, Glasgow Museums reopened it as the Gallery of Modern Art. And the library never fully left. A public library still operates in the lower level of the building today. So you can borrow a novel downstairs and see contemporary art upstairs, under the same roof. Few galleries anywhere combine the two so directly.

Step through the doors and the scale changes. The main hall is a long, high space lined with columns, with a richly decorated ceiling overhead. This was the trading floor of the old Exchange. Today it often holds large installations and works that need room to breathe. Light falls from above, and voices soften in the space. Take a moment to look up before you look at the art. The ceiling alone tells you how much money once moved through this room.

The collection itself belongs to Glasgow Museums. It focuses on art from recent decades, with a strong thread of Scottish and Glasgow-based artists. The city has a celebrated art school, and for a generation it has produced painters, sculptors and video artists known well beyond Scotland. Exhibitions change regularly, so what you see today may be gone next season. GoMA often takes on social themes too — identity, community, human rights — and invites local groups to take part.

That changing programme is part of the point. This is not a quiet treasury of fixed masterpieces. It is a working gallery that tries to start conversations, and sometimes arguments. Some visitors love a piece; others walk past puzzled. Both reactions are welcome here. Read the wall labels, sit on a bench, and give a work a full minute before you decide. Modern art often opens up slowly, the same way a stranger does in conversation.

When you step back out into the square, try to see the whole building in one glance. A tobacco merchant's home. A bank. A trading exchange. A library. And now a gallery of the present day, guarded by a bronze duke in a plastic hat. The stone has carried each of these lives without changing its calm face. Listen again to the buskers and the footsteps, look up at the cone catching the light, and let the city carry on around you.