Less than a decade after Scotland's largest city reigned as European Cultural Capital, it's back as 1999 UK City of Architecture and Design. And both times, to the delight of all Glaswegians, Edinburgh was among the also-rans in hard-fought contests for these coveted titles.

Glasgow's claim rests on an illustrious design tradition, peopled by such great talents as Charles Rennie Mackintosh and the lesser-known, but no less inspired Alexander "Greek" Thomson. It is also being billed as the "coolest" city in Britain, with a profusion of pubs, restaurants, cappuccino bars and night-time venues to suit all tastes.

This year, as if to copper-fasten its high cultural reputation, Glasgow is staging "the largest and most ambitious celebration of architecture and design ever attempted anywhere in the world". And the scope of its 300-plus events is to be national and international, as well as community-based and city-wide; in other words, something for everyone.

Its director, Deyan Sudjic, aims to "pull architecture and design out of the professional ghetto" by making it more relevant to the sort of people who might bring the house down for Billy Connolly. Inevitably, this involves an "in-yer-face" approach, taking events to real ghettos such as Easterhouse, where design never got much of a percentage.

The centre-piece of 1999's programme is The Lighthouse, intended as Scotland's permanent centre for architecture and urban design. It is being created by renovating and extending Mackintosh's earliest public building, the former Herald newspaper offices on Mitchell Street - just one block east of Glasgow's splendid Central Station.

The building, with its characteristic "bluebell" tower, had been lying derelict for more than 15 years, despite its acknowledged authorship by Glasgow's greatest architect. Its location could hardly be worse - right across the street from one of those awful, grey open-decked multi-storey car-parks that were all the rage in the early 1970s.

So far, The Lighthouse may only be glimpsed through scaffolding and green mesh; it will not be finished until June. It is clear from the plans, however, that Glasgow architects Page and Park have treated the Mackintosh building as a mere backdrop for their own ideas and those of the quirky Spanish interior designer, Javier Mariscal.

It seems somewhat strange that the architectural centrepiece of Glasgow's latest "party" will be ready only in June, half-way through the year. Apparently, the organisers had to put an awful lot of effort into raising funds for their ambitious £34 million programme, of which the City Council is contributing £8.5 million.

Capital projects, such as The Lighthouse, are costing a total of £22 million, with funding coming from Britain's National Heritage Lottery Fund, the Scottish Arts Council, the Glasgow Development Agency and the European Regional Development Fund. All can see the benefit of consolidating Glasgow's reputation as a cultural centre.

When it finally opens, behind an ultra-modern wall of glass and steel, The Lighthouse promises an exciting series of exhibition galleries, seminar rooms, cafe, shop and all the latest in information technology - some of it showing the best of C.R. Mackintosh. It will also have a crow's nest, offering spectacular views over the city.

Its first major exhibition will be "The Unknown Genius", illustrating Alexander "Greek" Thomson's remarkable legacy to Glasgow and his innovative uses of neo-classicism. No mere Greek revivalist, he was severely critical of others who copy what's past: "They failed to master their style, and so became its slaves," he once said. The Thomson exhibition has been curated by Gavin Stamp, tireless enthusiast and campaigner for Glasgow, and author, under the pseudonym Piloti, of the Nooks and Corners column in Private Eye. It is accompanied by an excellent map and guide for architectural tourists who would wish to see it all for themselves.

This is one of a special set of six beautifully-produced architectural guides to Glasgow - including one on interesting bars and restaurants. Many of these are located in the trendy Merchant City area, such as Air Organic ("small areas of beautifully saturated coloured light"), but there are old reliables, too, such as the art deco Rogano.

The series also includes a guide to Glasgow's architecture for children and young people. This is no tokenism, either; 1999 has seen the inauguration of a three-year rolling programme of residencies for architects and designers in schools. In this way, some 50,000 future "consumers" will benefit from being got while they're young.

There are lots of exhibitions, including three featuring such modern masters as Alvar Aalto, Frank Lloyd Wright and Ludwig Mies van der Rohe. On the brink of electing their first parliament, the Scots are particularly interested in Aalto and how he helped to define the identity of another newly-independent country (Finland).

Another exhibition, "The Architecture of Democracy", puts a spotlight on the connection between political practice and architectural ideas - exemplified by the confrontational nature of Pugin and Barry's House of Commons and the radical reworking by Enrico Miralles' of the whole notion of a Scottish Parliament, now under construction.

But perhaps the lasting impact of Glasgow 1999 will be its buildings - notably the "Homes for the Future" project. Just as Berlin still benefits from the lasting achievements of its international building exhibitions, Glasgow will be able to point to its own oasis of innovation - or, at least, how it sees housing developing in the 21st century.

The location at Glasgow Green, on the eastern edge of the city centre, is a building site scheduled for completion in July. Each block has been designed by a different firm of architects, including Rick Mather, RMJM, Ushida Findlay, Ian Ritchie (designer of Dublin's Millennium Spire) and Elder and Cannon, a highly rated local firm. The aim of the project is to "explore new responses to changes in urban living, examining issues such as changing family structures, environmental and energy concerns and designing for special needs". It will be accompanied by an exhibition looking at how the 20th century has wrought enormous changes in our concept of "home".

Civic improvement is also rife. Five new public spaces are planned to transform high-profile derelict sites, beautiful stone paving and street furniture are appearing in newly-traffic calmed areas of the city centre and - horror of horrors - the whole of George Square, in front of the City Chambers, has been redone in red tarmac. Red Square!

But Glasgow's largest single development during 1999 has nothing to do with its official programme - the opening, in April, of the Buchanan Galleries, a major in-town shopping centre. With its 600,000 sq ft of retail space and multi-storey parking for 1,000 cars, this huge magnet is also part of Glasgow's drive to keep itself firmly on the map.

Mark O'Neill, Cork-born curator of the Glasgow museums, says the city is much more laid back now than it was in 1990, when it really needed that designation as European Cultural Capital. "It doesn't need 1999 so much, which is why it seems less frenetic and will probably leave more of lasting value", he believes.