“Harry Potter” reunion. And it’s finally happening.

Daniel Radcliffe, Rupert Grint, Emma Watson, Tom Felton and more of the Hogwarts gang will travel back to the magical school with filmmaker Chris Columbus for an HBO Max special to celebrate the 20th anniversary of the franchise’s first film “Harry Potter and the Sorcerer’s Stone,” which premiered in the U.S. Nov. 16, 2001.

“Happy 20th Anniversary Potterheads!” Watson wrote on Instagram Tuesday. “Thank you to the fans that have continued to show their support well after the last chapter closed. The magic of the world wouldn’t exist without you. Thank you for fighting to make it such an inclusive and loving place.”

Felton added, “Is this what school homecoming is like?”

HBO Max announced the retrospective special, “Harry Potter 20th Anniversary: Return to Hogwarts,” Tuesday, corresponding with the anniversary. The special will arrive Jan. 1 and feature in-depth interviews and cast conversations and give a behind-the-scenes look at the making of the franchise, according to a press release.

The Gryffindor trio and Felton will be joined by memorable cast members like Helena Bonham Carter, Robbie Coltrane, He Who Must Not Be Named (Ralph Fiennes) and others. “Harry Potter” author J.K. Rowling’s involvement in the special was not noted in the release.

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HBO released a teaser trailer for the special in which we see flashbacks from the Harry Potter films and hear Albus Dumbledore’s voice saying: “Mysterious thing, time. When in doubt, I find retracing my steps a wise place to begin.”

It appears Watson took Dumbledore’s advice. In a commemorative Instagram post, Watson turned back the hand of time – much like Hermione did with a Time Turner in 2004’s “The Prisoner of Azkaban” – and reflected on her journey in the “Harry Potter” franchise.

“Harry Potter was my home, my family, my world and Hermione (still is) my favorite fictional character of all time,” she wrote Tuesday on the 20th anniversary. “I think a journalist once said it was irritating how many times during an interview I mentioned how lucky I was and started counting… BUT I (expletive) WELL KNEW!!! And still know.”

She added: “I still miss the crew who made these films all the time. Thank you for all of your hard work too – I know your contributions sometimes get overlooked.”

In a statement, Warner Bros. president Tom Ascheim said the the retrospective special “is a tribute to everyone whose lives were touched by this cultural phenomenon—from the talented cast and crew who poured their heart and soul into this extraordinary film franchise to the passionate fans who continue to keep the Wizarding World spirit alive 20 years later.”

It was 20 years ago when three children – Radcliffe, Watson and Grint – were plucked from obscurity and thrust into the international spotlight, portraying the stars of one of the most well-known stories of all time in a big-budget franchise adaptation.