It's probably as revolutionary and ground-breaking as Mozart gets these days. A German-based quartet staged Saudi Arabia's first-ever performance of European classical music in a public venue before a mixed gender audience. The concert, held at a government-run cultural center, broke many taboos in a country where public music is banned and the sexes are segregated even in lines at fast food outlets. The Friday night performance could be yet another indication that this strict Muslim kingdom is looking to open up to the rest of the world. A few weeks ago, King Abdullah made an unprecedented call for interfaith dialogue with Christians and Jews - the first such proposal from a nation that forbids non-Muslim religious services and symbols. "The concert is a sign that things are changing rapidly here," said German Ambassador Juergen Krieghoff, whose embassy sponsored the concert as part of the first-ever German Cultural Weeks in Saudi Arabia. "Evidently the government has decided that a minimum of openness in our new world economy and in our information-based world is necessary for us and also for good understanding among cultures," he added. Public concerts are practically unheard of in the kingdom. Foreign embassies and consulates regularly bring musical groups, but they perform on embassy grounds or in expatriates' residential compounds, and the shows are not open to the public. In the past couple of months, however, there has been a quiet, yet marked increase in cultural activities in Saudi Arabia. Lectures and a couple of segregated folk music performances were held on the sidelines of Riyadh's book fair. And Jiddah's annual Economic Forum opened with a surprise this February - a performance of Arab and Western music. "For half an hour, we did not quite know whether we had stumbled into an unknown Jiddah nightclub or whether it was some amazing mistake that would suddenly stop," wrote Michel Cousins in the English-language daily Arab News, describing the 30-minute show. Friday's concert of works by Mozart, Brahms and Paul Juon was the first classical performance held in public in Saudi Arabia, said German press attache Georg Klussmann. It was advertised on the embassy's Web site with free tickets that could be downloaded and printed. The excitement in the 500-seat hall was palpable as the largely expatriate audience walked in. "We have not done a concert like this before," German diplomat Tobias Krause told the audience at the start of performance by the Artis Piano Quartet. Those gathered applauded enthusiastically after each piece and were treated to an encore. Sebastian Bischoff, the German cultural attache, said the mission had received permission for the event from the Ministry of Information and Culture, which runs the King Fahd Cultural Center where the concert took place. Japanese pianist Hiroko Atsumi, the quartet's only woman, said there was some debate before the concert about whether she should perform in an abaya, the enveloping black cloak all women must wear in public. She ended up settling on a long green top and black trousers. Among the first to arrive was Faiza al-Khayyal, a retired Saudi educator, with her 15-year-old daughter. "I came here for her sake. She loves classical music," said al-Khayyal. "There are cultural activities at embassies, but we don't get invited to them." Al-Khayyal said she had inquired about seating arrangements and was told the audience would be mixed. Did she mind bringing her daughter to a mixed gathering? "It's OK with me," she said, and then added with a smile: "I'm with her." Faleh al-Ajami, a university Arabic language professor, brought his wife and two sons to the concert - a rare opportunity for the whole family to do something fun together. "It's a good step to introduce Saudis to classical music," al-Ajami, 50, said during the intermission. "I was amazed at the sounds coming from the musical instruments," said his son Ziad al-Ajami, 11, a fan of hard rock. "I've never been to a live concert before." For the expatriates, the evening was an opportunity to have a normal evening out in Riyadh, a city with no movie theaters and where women are not allowed in outdoor cafes. One foreign couple held hands, while another husband put his arm around his wife's shoulders - rare public displays of affection in the kingdom. The mutuwwa, the dreaded religious police tasked with enforcing public morality, were nowhere to be seen for a change. "I'm glad for an opportunity like this," said Mary Ann Jumawan, a 40-year-old administrator at the South Korean Embassy. "It's the first time in nine years here as a married couple that my husband and I go to a location like this." But not everyone was impressed. Abdullah al-Sabhan, his brother and three friends received invitations from a German business associate, but after half an hour, they snuck out. "I'm bored," said al-Sabhan, 26, an engineer who prefers Egyptian pop music and had never heard of Mozart. "Let me leave before the second piece begins." His brother, Saud, dismissed the notion that gatherings involving men and women together might one day become the norm. "Saudi society wouldn't accept it. And girls aren't used to such mixed gatherings," he said, adding that if he had a sister, she certainly would not have been allowed to attend.