By Sarah Rainsford
BBC correspondent, Moscow
A bold French design has been chosen by an international panel of judges as a new home for Russia's Mariinsky Theatre.
The design will create a big open space for opera
The St Petersburg company, better known in the West as the Kirov, has long outgrown its current imperial building, where its directors complain their creativity is being stifled.
The Russian authorities invited proposals for a new design from all over the world, but the jury's final choice is proving controversial.
It has been described as a golden sarcophagus. Those more charitably inclined call it a cocoon.
Whichever way you look at it, the winning design for the new Mariinsky Theatre will change the classical landscape of St Petersburg forever.
French architect Dominique Perrault is best known for his minimalist national library in Paris.
His vision for St Petersburg is far more extravagant - a series of angular black marble structures covered in a giant golden shell.
Perrault: Golden envelope symbolises city's monuments
The dramatic French design beat off equally striking submissions from an international field.
They included a giant hand, a grand piano and a vision in glass cubes and canopies dubbed "the rubbish bags".
The contest has sparked a lively debate in a conservative city, famous for its pastel palaces and glittering spires.
The Frenchman's supporters say his winning golden canopy will mirror the vast domes of St Petersburg's cathedrals.
The architect himself claims his theatre will sit in perfect harmony with the traditional, turquoise original.
His opponents are not convinced.
They call the annex a nasty blot on the landscape.
Architectural niceties, though, are the last thing worrying the theatre's artistic director.
Valery Gergiev is overjoyed the expansion has finally been approved.
And with a new modern space to work in, the Mariinsky will be able to stand proud once again - alongside its international rivals.