Moscow's Bolshoi Theatre will reopen in October fully restored to its original 19th-century appearance, a subcontractor said Monday.

But while the look will belong to the czarist era, the technology will be completely updated, opening the door for more innovative productions.

"Directors could do things that were impossible before," according to Mikhail Sidorov, a spokesman for Summa Capital, the second contractor to take over the restoration.

The building, dating from 1825, has been closed since 2005 and construction has been plagued by delays, cost overruns and accusations of corruption.

Authorities say at least $660 million has been spent so far, surpassing the original estimate by 16 times. The Moscow government has fired several subcontractors and investigators are looking into whether funds were misused.

The theatre is to have its czarist insignia restored and be brought back to its former glory with embroidered silk tapestries and the original violin-shaped auditorium.

The acoustics will be improved with fir and papier-mache panels, and hydraulic devices are being installed in the floor. The redesigned floor is expected to be easier on the feet of dancers.

The historic building was threatened in part because it stood on oak stilts sunk into Moscow's moist soil. After underground watercourses were contained within pipes, the oak stilts dried up and collapsed.

It was further damaged by fires and Nazi bombing in 1941. A Soviet-era remodelling that included filling the hollow resonator under the orchestra pit with concrete ruined the acoustics.

While some arts funding was threatened after the fall of communism, the Bolshoi Ballet and Theatre maintained their international reputation and rebuilt their financial base. They have continued performing in the past six years in a nearby theatre.

In the meantime, 3,500 people are still at work on the restoration.

With files from The Associated Press