One of Charles Rennie Mackintosh's most mysterious, little-known buildings has been restored at a cost of £1m.

The Queen's Cross Church, in Maryhill, Glasgow, is regarded as a curious gem of world architecture and contains some of the iconic architect's purest work.

Experts struggle to explain the meaning behind some of its details, including carvings of birds and bees on the communion table and chairs, which could be a teasing reference to sexual reproduction.

The church, built in 1897-99 for the Free Church, contains design allusions which are gothic, pagan and Roman Catholic, such as an Italian-style water bowl built into the stone.

It even includes an imitation pre-Reformation rood beam, a very non-presbyterian, English symbol seen nowhere else in Scotland.

There is also a special site for an organ, although no music is played in the Free Church.

One magnificent stained glass window features a giant blue heart, the other a puzzling green T shape, which may or may not be Mackintosh's stylised version of a cross.

"We'll never know because he never wrote down the meanings. It is the mystery of Mackintosh," says Stuart Robertson, the director of the Charles Rennie Mackintosh Society.

"This was the only church he designed. It is pure, uncluttered Mackintosh. It's also very playful and eclectic. How did he explain these details to the Free Church?"

The 12-month restoration by specialist builders Hunter & Clark, entailed work on the roof and stonework. Windows were taken out and restored, the building was rewired and heating was installed.

Richard Bennie, Hunter & Clark's managing director, said: "We have a long association with the building, but this phase was particularly challenging. It involved the manufacture of fitted furniture in the Mackintosh style, extensive repairs to the stained glass windows and the dismantling and repositioning of the renowned Howarth Screen."

Funding for the project came from the Heritage Lottery Fund, Scottish Enterprise Glasgow and Glasgow City Council, plus 12 other charitable trusts. The refurbished church contains a shop and resource centre and is expected to attract an increasing number of tourists.

Part of the funding will pay for a Mackintosh development officer to be employed for three years.

The building, described as "mystical" by Mackintosh's biographer Thomas Howarth, faced threat of demolition in the 1970s.

It ceased to be a parish church in 1976 and was only made wind and watertight in the 1980s through the efforts of the newly formed Charles Rennie Mackintosh Society.

Ranald MacInnes, principal inspector with Historic Scotland said: "Queen's Cross Church is of international significance and is an asset, not just to Glasgow but to Scotland as a whole."

Colin McLean, Heritage Lottery Fund manager for Scotland, said: "The works will ensure that this wonderful building can continue as a centrepiece in Glasgow's collection of historic buildings."

The church will reopen to the public on March 5.

  • Rescued and restored, now the debate begins
  • The Queen's Cross Church, built 1897-99, is the only Mackintosh church ever constructed. He submitted a project for the Liverpool Anglican Cathedral competition in 1903, but did not win
  • Thomas Howarth, Mackintosh's famous biographer, described the "curious form and alien character" of the church's tower. It was inspired by a medieval church in Merriott, Somerset
  • The rood beam, unique in Scotland, is a copy of the pre-Reformation beams in English churches which Cromwell destroyed. The beam defined the raised altar area into which only church officials could cross
  • The internal decorations are pagan in feeling and have much in common with Celtic and early Christian art
  • The church is very popular with Japanese visitors because of its heavy Japanese influences - the cantilevered galleries, double beams and pendants. Japanese students are known to burst into tears on entering
  • Sacred motifs of birds, their wings protecting seedlings beneath, appear all over the church. Mackintosh never explained the imagery, but it reoccurs right through his work
  • During the Second World War Dr Howarth, himself an architecture lecturer, changed the interior of the church by designing a screen to go under the gallery
  • "Novel to the verge of eccentricity" is how The Builder's Journal described the church in 1895. "Curious"; "not wholly coherent" are other descriptions