Sir Robert McAlpine and Wales Millennium Centre (WMC) have celebrated a major milestone in the construction of the international performing arts venue with a topping out ceremony.

The WMC has Welsh slate walls designed to look like dry stone walling - walls that led to a delay in starting the project as contractors decided the walls were too difficult to build. McAlpine came up with a solution that simplified the construction while retaining the concept and started work on the £104.2million project in February last year.

Key figures from McAlpine, the principal funders (£37million from the Welsh Assembly, £30.7million from the Millennium Commission and £9.8million from the Arts Council of Wales) and the WMC gathered together near the roof of the 37,000m2 development to mark the completion of the structure.

In a traditional ceremony that can be traced back to Roman times, an evergreen bough was nailed to the building to protect it from \'evil spirits\'. Sir Robert McAlpine\'s heritage was also acknowledged with a procession led by the company\'s trademark piper.

The WMC will host an international showcase of opera, musicals, ballet, and dance. It will include a world-class 1,900 seat lyric theatre for amplified and non-amplified sound, a studio theatre, a dance studio, a main concourse suitable for live performances, rehearsal halls, recording studios, bars, cafÈs, restaurants and shops.

The design also incorporates residential accommodation for Urdd Gobaith Cymru, a youth organisations, and will be home for six other leading Welsh cultural organisations. Sir David Rowe-Beddoe, chairman of WMC, said at the topping out ceremony: "Today we celebrate the completion of the structure and pay tribute to the accomplishment of Sir Robert McAlpine and the construction workers. This is a significant milestone on the road to the opening night in November next year."