It is Friday evening in Mechelen, and De Gouden Vis - The Goldfish - is packed to the gills. The bar is often like this, and no wonder: it's one of the best boozers I've discovered in Belgium, a nation not starved of superb places to drink. From its faded art-nouveau frontage to the tumbledown riverside terrace, the place radiates a raffish, beery charm, attracting young and old alike.
I end up squashed against a pillar (under a joke sign declaring: "Toilet out of order - please use far corner") and soon find myself chatting to a group of expensively-dressed twentysomethings. As successive bottles of Trappist ale work their little miracles, we prattle about everything from the EU elections to the putative sexual habits of Tintin. And then I commit a terrible solecism: I mention the "A" word. There is an almost audible frown.
"Antwerp? You want to know what we think of them?" says a woman in black Prada jeans and an ironic Iron Maiden T-shirt. "It's like this. In Brussels, they think they rule the world. But the people in Antwerp, they think Antwerp is the world."
It's not surprising that the Mechelaars should suffer from a touch of second-city syndrome. Mechelen lies just 15 miles south of Antwerp, its provincial capital and the more populous city by a factor of about six. Over the centuries that Antwerp flourished, Mechelen became something of a backwater. Worse yet, its neighbours to the south, Brussels and the university city of Leuven, did rather well, too.
But all this is now changing. Millions of euros of investment and some farsighted regeneration projects are transforming Mechelen. Canals, bricked over centuries ago to eliminate the threat of cholera, are being reopened, and a new floating walkway has turned the river Dijle into a valued thoroughfare again. Sharp boutiques, stylish restaurants, and designer hotels and B&Bs are springing up around the cobbled streets and squares.
Earlier in the day, I had explored the compact city, enjoying the fine Gothic architecture and the fashionable hotspots. As the carillons in St Rumbold's tower - there are two, with a total of 98 bells - chimed out a recital, I wandered around the Grote Markt and its surrounding streets.
Among the one-off boutiques to be found here is Awardt (Adegemstraat 3; 00 32 15 271 648, awardt.be), a quirky bag and hat emporium run by mother-and-daughter team Wies Dehert and Els Van den Berghen. Overlooking the river nearby is the eponymous showroom of jeweller Helga Kordt (Dijle 10; +15 261 373, helga-kordt.com), whose handcrafted creations are as beautiful as they are expensive.
Mechelen is particularly well served for bottle shops. Tobacco emporium Windels (Ijzerenleen 48; +15 287 093, huiswindels.be), a landmark since 1875, has lately diversified into spirits, pushing a vast range of rums and whiskies. De Wijnwinkel (Guldenstraat 2; +15 209 538, dewijnwinkel.be) in the 13th-century river tollhouse is another alcoholic Aladdin's cave. I had been rather hoping to take home a bottle of Gouden Carolus, a single malt distilled in Mechelen, but this proved to be sold out everywhere.
Back at De Gouden Vis (Nauwstraat 7, just off Vismarkt), I make my farewells and step outside on to Vismarkt, the former fish market on the river quay that is Mechelen's most potent symbol of regeneration. For years, the workhouse-like shell of the Lamot brewery was a hulking presence here. Shut down in 1995, the complex and its surrounding area became - in the words of a tourist-office leaflet - a very unsavoury place. Tonight, the glass facade that wraps around the recommissioned brewery - now a cultural centre, restaurant and exhibition hall - glistens in the fading light. Inside, diners in the upmarket Grand Café Lamot peer down imperiously on the bustle of quayside revellers. Vismarkt's transformation from eyesore to cafe quarter has been ratified with the opening of two hotels: a discreet Novotel (+15 404 950, accorhotels.com, doubles from €59) on one side of the Dijle, and the Hotel Vé (+15 200 755, hotelve.com, doubles from €98), a plush designer billet in an old herring smokery, on the other.
Some of the city's new designer B&Bs are just as eccentric, such as The Patio Houses. The living room of its one guest suite is a preserved 50s salon with Bakelite fixtures, but grafted on to this is a brutalist bedroom in bare concrete and brushed steel - and there's an unexpected, Tardis-like spa in the basement. Another characterful guesthouse is Dusk Till Dawn, an art deco period piece with two bedrooms.
But it's the bars that do it for me, and I can't think of anywhere that has such a close concentration of outstanding watering holes: not sterile style bars, but genuine Flemish "brown cafes", now being reclaimed by a new generation. Next to De Gouden Vis, I visit Den Stillen Genieter ("The Quiet Hedonist"), a Mechelen classic that offers a choice of more than 400 beers. Across the square is 't Ankertje, an outpost of Het Anker brewery - after the demise of Lamot, the only one remaining in Mechelen. There's no better place to try out a Gouden Carolus beer, once the preferred tipple of holy Roman emperor Charles V, who was brought up in Mechelen. I sit, sip and watch the nightlife develop on the square outside.
The next morning brings clear weather and a cloudy head: ideal conditions for a brisk walk up St Rumbold's tower. But first, I take breakfast in my hotel, the newly opened Martin's Patershof, a spectacular conversion of a 19th-century Franciscan church with many features left intact, including the altarpiece in the dining room.
The tower is an appropriate totem for Mechelen, a city that was briefly capital of the Low Countries before losing its court to Brussels in 1530. Around that time, the tower was planned to reach 167m, impressing Mechelen's precedence upon its neighbours. But, thanks to religious conflict, lack of funds or engineering difficulties - no one is quite sure which - the spire was never built, and the tower was topped out at just under 100m.
That's still an intimidating 514 steps for those who climb to the top, but it's worth the exertion. The tower has also undergone an expensive revamp, and at the summit is a new metal and glass "skywalk", which grants a breathtaking 360° vista over the pancake-flat landscape. In one direction, I'm able to pick out the tiny silver Newton-balls of the Brussels Atomium; in the other, the distant derricks of the port of Antwerp.
After a typical lunch at Brasserie 't Oud Conservatorium (Hotel Den Wolsack, Wollemarkt 16; +15 569 520, denwolsack.com) of white asparagus and Mechelen cuckoo - a particularly plump local breed of chicken - I head for the tourism office at the Grote Markt to pick up some leaflets. In the square I notice a bronze statue of a greatcoated midget with a grotesque rictus, and then come across a wooden effigy of the same figure inside. I ask the woman at the desk about its significance.
"That's Mechelen's mascot, Op-Sinjoorke," she tells me. "The original effigy used to be carried round in special processions, but in 1775, he was thrown up in the air, and someone from Antwerp caught him. The townsfolk thought he was stealing him, and beat the man up."
In these parts old rivalries die hard. Mechelen is a hidden gem among Belgium's cities. If you go, you know what not to mention.
• Eurostar (0870 518 6186, eurostar.com) fares from London St Pancras, Ebbsfleet and Ashford to Brussels start from £59 rtn; all Eurostar tickets to Brussels are valid to any Belgian station at no extra cost. Martin's Patershof (00 32 15 464 646, martins-hotels.com) has doubles from €119, B&B. Dusk Till Dawn (+15 41 2816, dusktilldawn.be) has doubles from €100. The Patio Houses (+15 46 0860, thepatiohouses.be) has doubles from €145. Further information: Tourism Flanders-Brussels (020-7307 7738, visitflanders.co.uk).
