OXFORD'S historic Holywell Music Room, the world's oldest purpose-built concert hall, is to be renovated.
A £2m appeal is being launched, with the 260-year-old venue to be doubled in size via an underground extension.
Down the centuries, the Holywell Music Room has played host to some of the world's greatest musicians and composers, including Haydn and Handel.
But a decision has been made to transform the iconic Oxford building into a 21st-century venue, following concerns from promoters about the cramped and outdated facilities.
The facelift would see a foyer, bar, green room and seminar room created below ground. An area under the main stage has previously been excavated and used as a music library.
Partitions on the ground floor are to be stripped away to create a spacious entrance hall while making a feature of the building's 18th-century spiral staircase.
The plans have been drawn up by the west Oxfordshire architect John Melvin, whose wife Julia is the secretary of the appeal that will be formally launched in October.
The building is sited in one of Oxford's most unspoilt streets on land owned by Wadham College. It is administered during term time by the university's Faculty of Music.
Mr Melvin said: "It is one of the most famous concert halls in the world and it has continued to play a remarkable role in the musical life of this country since the 1740s.
"But it does need bringing up to date. People now demand facilities like a bar and circulation space. The acoustics will, however, be uppermost in our minds."
While the present seating capacity for about 250 is unlikely to be increased, he hoped to replace the 1960s benches with comfortable. seating.
The building was designed by Thomas Camplin, Vice-Principal of St Edmund Hall, and a public subscription for its construction was set up at the beginning of 1742. It was opened six years later and was instantly hailed as one of the world's most acoustically perfect venues for chamber music. In its early years, Handel was in vogue and his music was often in the programmes.
The Holywell was restored and refitted in 1959-60 and since then has been in continuous use for performances by some of the world's most illustrious musicians and by local and university groups.
Mr Melvin said about £40,000 had already been raised. He believed the work could be completed in two phases, with the first part involving the restoration of the railings, staircase and original foyer, completed next year. The underground work was unlikely to get started before 2010. Mrs Melvin said: "The present green room would make a village hall committee blush. There is no warm-up space or places to lock-up instruments. This is an opportunity to make it the most distinguished chamber music hall outside London."