Meredith Mitchell’s two young sons were the first to notice the stone house with the turret tucked away in Lake Forest nearly seven years ago. “Mommy, oh my gosh, did you see that castle back in there? Will you get that for us? It’s so beautiful,” they said. She told them sure, if it ever went on the market.

Not 24 hours later, Mitchell’s real estate agent, Elizabeth Wieneke of Griffith, Grant & Lackie, texted her about a listing that had Mitchell’s name on it. You can guess where this is going. “The boys and I ran over to look at it, and we were like, ‘Yes, it’s perfect,’ ” says Mitchell, an interior designer. She is now putting the house back on the market for just under $5 million, as she looks for a new project.

Griffith, Grant & Lackie founder John Griffith was known for working with architect Howard Van Doren Shaw to develop the suburb’s Market Square, which opened in 1916. Shaw protégé Stanley Anderson later designed this English country–style mansion for Griffith at 800 North Sheridan Road. The five-bedroom house sits on almost an acre in the Lake Forest historic district.

Mitchell was taken by its strong bones and sweeping natural light but felt the house needed to be brought “up to speed for the modern family.” After closing in mid-2014, she worked with a contractor and an architect to give it a major renovation.

The team excavated to create a 1,900-square-foot finished basement and replaced a ’90s addition with a two-story version that blends better, bringing the total square footage to 7,500. The family room opens to the kitchen and spills out through six sets of French doors onto a patio with a pergola lined by wisteria and twinkle lights. “It’s the best party pad ever,” Mitchell says.