I saw this on Newsweek – Man Finds Secret Window Hidden Behind Wallpaper in 19th-Century Home: https://www.newsweek.com/secret-window-hidden-wallpaper-19th-century-house-1621977. Longer article.
BY REBECCA FLOOD ON 8/23/21
A man discovered a secret window hidden behind wallpaper in his house, thought to date back to the 19th century, as he lovingly renovated the property.
Howard, an author, has been painstakingly removing all the woodchip wallpaper throughout the house—similar to popcorn style—when he found something unusual lurking behind the hardboard.