King Charles III is offering royal watchers a rare look at one of his private residences. The trailer for Charles' upcoming documentary, Finding Harmony: A King's Vision, dropped on Thursday, January 1, and showed the 77-year-old monarch looking relaxed at home. Fans quickly noticed that the never-before-seen residence was none other than his Gloucestershire countryside home, Highgrove House. One clip showed Charles smiling while watching his old speeches about the environment from a plush chair in what appeared to be a projection room. He was also filmed walking through the Highgrove Arboretum. Courtesy of Passion Planet A second royal residence, Dumfries House, is also briefly shown. This home holds the headquarters for The King's Foundation's charity, which works to provide services and education on "sustainability, farming and agriculture, traditional arts and crafts, health and wellbeing, and architecture and urbanism," per its website. "I think we need to follow harmony if we're going to ensure that this planet can support so many," Charles said in the trailer. "It's unlikely there's anywhere else." Inside Royal Family Properties: Who Lives Where - And How Much They Pay Finding Harmony: A King's Vision is set to stream via Prime Video early next month and "will tell the story of His Majesty The King's lifelong commitment to the philosophy of Harmony and the environment, urging viewers to protect our planet and create a more sustainable future for the next generation," according to its official description. Kate Winslet is narrating Charles' story, which will be told through his work with The King's Foundation's charity. Charles' lifelong work on protecting the environment assisted in his decision to add Highgrove House to his real estate portfolio in 1980. The home acts as one of his primary residencies with wife Queen Camilla. While the house has remained private, the Highgrove gardens are open to the public from April through October. The trailer released on Thursday puts focus on the home's garden. Archival footage even shows Charles participating in the seasonal U.K. tradition of hedgelaying. "As a teenager, I watched in horror as miles and miles of such a wonderful part of the British landscape was grubbed up in the name of agricultural progress," Charles said in a 2021 speech, when discussing the importance of hedgelaying, which encourages growth of the greenery. King Charles Records Surprise Podcast With Cate Blanchett He added, "Hedges which had stood for hundreds of years - even thousands - disappeared in an instant and now our hedgerows are under a new threat of disease, with ash dieback threatening to destroy the vast majority." Along with Charles, the upcoming documentary will also feature interviews with several individuals who support the king's message of harmony. Archival footage from the early days of his work with the environment will also be showcased. "I have dedicated much of my life to the restoration of harmony between humanity, nature and the environment," Charles said in a 2020 speech, which he rewatched in the trailer. "Quite frankly, it has been an uphill struggle.' Finding Harmony: A King's Vision will be available to stream via Prime Video on February 6.