Singing in Vienna: holidays designed for choristers

The clock has just ticked past midnight and I'm standing on a stage in front of the altar of Vienna's most spectacular Baroque church, the Karlskirche, mesmerised by the architectural riot of marble, gold and cherubs going on around me.

I'm in the second front row of a choir of more than 90 other singers, all clutching our music scores and awaiting the entrance of English conductor Jeremy Jackman, who will be leading us through Mozart's Requiem. Meanwhile, an orchestra of local classical musicians – young women with flowing hair and cool-looking dudes with man-buns – are tuning up the 18th-century instruments they'll be playing for this performance of the heartbreakingly beautiful funeral mass that Mozart was working on when he died, aged 35, in his apartment on Vienna's Domgasse. Less than 1.5 kms away from where I'm standing now, the flat is now the site of a Mozart museum.

We've been rehearsing this work for two days now. We've all sung it before with our different choirs at home – me with Melbourne's Star Chorale, every one else with a range of choirs around the UK . But most of us have never sung together until our first rehearsal in a studio at Austria's ORF, the equivalent of the ABC, less than 48 hours ago.

Singing the Requiem in Vienna, where Mozart lived and worked, has added another layer of meaning to the music for me. During the two weeks I've just spent in Vienna, I have become besotted by the history of the Habsburgs, the Austrian dynasty that ruled great swathes of Europe from the 15th century until the end of World War I and who seem to have either built or owned every historic palace or art collection I inspect.

Mozart, it seems, was one more of the family's treasures. Eventually a composer at the court, he gave his first concert, aged six, at the Habsburgs' extravagantly baroque Schoenbrunn Palace, where he reportedly jumped onto the lap of a delighted Empress Maria Theresa. Noted for expanding Habsburg influence by marrying her daughters off to other European royalty, she is my second favourite Habsburg empress. My favourite remains the extraordinary 19th- century Empress Elisabeth – or "Sisi" – the rebellious royal who remains Austria's Princess Diana.

Our performance is timed to end at 1am on December 5, the hour of Mozart's death in 1791.This fact is a selling point for this concert, advertised all over the city with posters bearing the words "Mozart Requiem zur Todesstunde (at the death hour)".

Although the Requiem is often performed in Vienna, the church is packed. There are even people in the little oratories above the altar; these are the equivalent of boxes at the opera.

The audience look pretty pleased to be here. But none of them could be more excited than us choristers. Unlike the orchestra, the conductor and the soloists, all professional musicians, we are amateurs, only here because we are indulging in the fashion for "activity holidays".