Everybody knows the Royal Albert Hall. It is seared on the national psyche. Ask people what the interior of the Royal Festival Hall, or even the Royal Opera House, looks like and plenty of them will have absolutely no idea. But the Albert Hall - no problem. That deep red oval, packed with audience, musicians and choir, is its own logo. It may be acoustically imperfect, it may at times be uncomfortable, but when it comes to shared cultural experiences, it has no peer.

The 5,300 seat auditorium is Eric Clapton's preferred venue. It's best known for music, but boxing and tennis also take place there. It made the reputation of Cirque du Soleil in this country. It stands alongside the Royal College of Art, with Imperial College behind - the embodiment of Prince Albert's vision of an area that would fuse arts and sciences. His freshly-gilded statue gazes across at it from his High Victorian kitsch monument in Hyde Park. Behind the Hall, on the newly-restored South Steps, you find Albert again, this time as the centrepiece of the Memorial to his Great Exhibition of 1851. This monument has also been restored. But what you need to know is that there is now a lift shaft inside it.

The lift is there to take technicians deep underground. There they enter a 21st century world of humming machinery and blinking lights, for underneath the South Steps is a subterranean kingdom, an Albertian iceberg. This invisible new building contains not only air-conditioning equipment (which will soon be delivering fresh air to the auditorium via a tunnel newly hand-dug by two miners), not only a proper loading bay and scenery get-in for the first time in the Hall's history, but also a big chunk of new dressing rooms and offices. You won't see any of this. What you will find, however, is that, as work proceeds, far more of the original Hall will now be given over to the customers. For instance, the basement maze of old dressing rooms will soon be demolished to make new foyers and bars.