Culture to bloom in Barangaroo bunker

Tenders will soon be called to build Sydney's newest cultural facility - an underground space almost four times the size of the Opera House concert hall.

Set above a two-level car park, the 100,000-cubic metre cultural ''void'' will be constructed like a giant bunker hidden beneath a new headland to be built on the northern tip of Barangaroo.

Plans for the shell have been approved but no decision made on what it will be used for. Planning documents say that will be determined in the future ''depending on what Sydney needs''.

That sequence of decision-making has left some architects bewildered. ''It would be nonsense to construct a space without knowing what you are going to put inside it,'' said Peter Webber, a former NSW government architect and now emeritus professor of architecture at the University of Sydney.

''No architect in their right mind could design a space like that without knowing what you could put in it.''

Within months, the government's Barangaroo Delivery Authority will call tenders to build the new natural-looking headland designed by the US landscape architect Peter Walker.

Including the cultural void within, it will add just $8 million to the cost and will have ''maximum flexibility'' for any fit-out.

To support the park above, columns will be placed at 8.4 metre intervals on a 21 metre grid according to approved plans, but the authority said those pillars would not stop the space being used as a theatre or performance space one day.

''[It] provides for a range of cultural uses, such as a gallery, museum, performing arts space, artists' studios and education and learning facilities,'' the spokeswoman said.

In a last-ditch attempt to stop the plan proceeding, Professor Webber has written a letter to the Premier signed by more than 60 prominent urban planners and architects criticising the proposed headland and the loss of deep-water berths it will involve.