IN PHILADELPHIA, Malcolm Lazin is among the leading activists who have advocated for LGBT civil rights. As executive director of Equality Forum, he has helped turn gay pride in Philadelphia into a days-long annual celebration and exploration of LGBT issues.

This year on the Fourth of July, he's bringing things back to where they started - Independence Mall - for a ceremony honoring the 50th anniversary of a 1965 protest there that has come to be known as one of the earliest "steppingstones" to the landmark 1969 Stonewall riots and the gay and lesbian civil-rights movement that followed.

It's part of a four-day Equality Forum that will bring LGBT civil rights teach-ins to museums around town and a wave of parties and other events to the Gayborhood. (Full details are at lgbt50th.org.)

The Forum is also expected to bring joyous throngs to Philadelphia from far and wide, especially following yesterday's landmark Supreme Court ruling, which Lazin called "stupendous" and "monumental."

"It's a national celebration," Lazin said. "We're expecting people from all over the country to join us." Extra-special guests include Jim Obergefell, plaintiff in the gay-marriage court case.

Lazin spoke with Deborah Woodell shortly before the Supreme Court decision was handed down, and he updated the Daily News yesterday with his ebullient reaction.

Q Can you tell readers what the significance is of having such a huge event on July Fourth?

Well, it really relates to what happened here on July 4, 1965, in front of Independence Hall, when, for the very first time, activists from multiple cities gathered to demand equality for gays and lesbians.

In many ways, it really was transformative and certainly a landmark event in terms of LGBT civil rights. And so, we're obviously taking the ceremony on Saturday, July Fourth, back to where the gay pioneers launched the movement.

Q I know Barbara Gittings passed away a few years ago. Are there any gay pioneers attending the ceremony?

There are still some gay pioneers that are living, and a number of them will be joining us onstage . . . Not only will there be gay pioneers, but also James Obergefell, Edie Windsor , Judy Shepard , Bishop Gene Robinson and any number of other major leaders, in terms of the movement.

And Wanda Sykes will be the master of ceremonies for the ceremony itself.

Q I have to ask you, how did Wanda Sykes come about as the host? She might not be considered a typical host for such a prestigious event.

Well, no, I think I would actually differ with that. She certainly has been MC for a number of major events. She's out. She's married. She and her spouse are parenting children. So I think she's an excellent choice.

Q The Independence Mall area does get a little busier around the Fourth of July, so how were you able to steer the powers that be to be able to get this event on this day?

Well, you know, certainly the starting point is getting a permit from Independence National Historical Park, or National Park Service permit. And I must tell you that the park could not have been more welcoming.

They take really truly great pride in the fact that this is where the LGBT civil-rights movement was launched.

As you know, there is a gay pioneers historic marker at 6th and Chestnut, directly across the street from Independence Hall. And they had been hugely supportive.

The other thing I think that is really incredible is, by virtue of the 50th anniversary, it really empowered major institutions to think about how they would all participate.

There is a wonderful LGBT history exhibit at the National Constitution Center, which, in and of itself, would be hugely noteworthy.

But the reality is that there are five major mainstream institutions that are holding LGBT exhibits: the African-American Museum; the Free Library is doing a special Barbara Gittings exhibit; the Independence National Historical Park in the Liberty Bell Center is doing an exhibit; and the National Museum of American Jewish History.

Never in the history of the gay movement have there been five institutions simultaneously putting on an exhibit.

Q Were there any kind of logistical matters that needed to be addressed? Because the city is so crowded at that time of year.

We were obviously very respectful of those events that occur annually on July Fourth. The ceremony, the LGBT 50th anniversary ceremony, which will be one hour, is scheduled in the afternoon, at a time when there were no other competing events.

The other thing - I think I'd call serendipity, or good fortune or timing - is the Supreme Court's marriage equality decision yesterday. . . We think there will be a lot of people who will want to participate in a national celebration.

Certainly, given Philadelphia's proximity to New York and Washington, and Independence Mall being only one of two national malls in our country, it's a perfect place to celebrate 50 years and a landmark civil-rights decision.