Angelika Baldow and Gudrun Pannier, both 36, were the first couple to exchange vows at the town hall in Berlin's Schoeneberg district, long a center for Germany's lesbian and gay community.
"I feel great. This is very symbolic a message that Berlin is a tolerant city," Gudrun Pannier said after the ceremony. "It is the fulfillment of a dream, but it is just the beginning. We haven't got equal rights yet."
Wearing matching tailcoats and white bow ties, the couple kissed as district registrar Gisela Assmann formally sealed their new status as Frau and Frau Pannier. Cameras flashed as the two cut a three-tier chocolate cake topped with two marzipan brides and a rainbow flag of the gay pride movement.
"I am delighted. We don't need to hide anymore. We are no longer seen as sick or criminal," said Martin Beer, a rector and long-time friend of the happy couple who met six years ago.
Berlin's reputation for tolerance goes back to the 1920s when meeting places and clubs for gay men and women flourished alongside the city's racy cabarets.
That way of life was brutally suppressed after Adolf Hitler's rise to power in 1933. Gays were persecuted and sent to concentration camps.
Gay life rebounded in Berlin after the war, although male homosexuality was not decriminalized in West Germany and in the former communist East Germany until the late 1960s. Berlin's new mayor recently made headlines when he became the first senior politician to publicly come out as gay.
Despite broad public support for the reform, opposition conservatives tried to block the law, which was championed by the environmentalist Greens and supported through parliament by their ruling Social Democrat coalition partners.
But last month the constitutional court in Karlsruhe dismissed appeals by the conservative-ruled states of Bavaria and Saxony against the law, which the states said was an attack on the family values enshrined in the constitution.
The court will give a final decision on whether the legislation contravenes the constitution next year.
Under the new law, lesbians and gays who register their relationships will have the same inheritance rights as heterosexuals, may share a common surname, and their foreign partners will be allowed to join them in Germany.
But the law does not accord lesbian and gay couples the tax advantages granted to heterosexual married pairs or the right to adopt children. The relationships are not officially called "marriages" but "registered life partnerships."
Ceremonies took place in cities across Germany, one involving 15 gay couples who tied the knot at the same time in Hamburg. The German Lesbian and Gay Association (LSVD) expected dozens of gay marriages on Wednesday and hundreds in the next ew weeks.
"The registration of life partnerships still does not bring equality, but is a great leap forward in the right direction," LSVD spokesman Manfred Bruns said in a statement.
Bruns criticized states like Bavaria, which have made no provision for registering gay partnerships, or only minimal ones. "We call on Bavaria to give up its policy of harassment of lesbians and gays," he said.
Gay protesters waving rainbow flags demonstrated in Munich against Bavaria's stance. The constitutional court is to rule next week on a case brought by gay campaigners to force the southern state to register their partnerships.
Earlier this year, the Netherlands legalized gay marriage, and in 2000, Vermont became the first state to formalize civil unions allowing many marriage benefits. The Vermont statute has become a rallying point both for gay rights advocates and opponents.
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