If you’ve taken a tour of The Breakers, the 70-room Newport “cottage” built in the late 19th century and the most popular mansion in properties owned and run by the Preservation Society of Newport County, you know its opulence and elegance. Hundreds of thousands are drawn to the magnificent mansion, to view things like its celebrated Gold Room, and the Great Hall with its 45-foot high ceilings, and its ornate architecture, art and furnishings.

Ever look down and wonder what’s going on below? Wonder no more, and take the newest tour of the Preservation Society: Beneath the Breakers, which takes tourists on a guided tour for a fascinating look below ground at the subterranean machinations that made the massive mansion run so smoothly. Prior to the tour, there was an 18-month, $1.5-million restoration of the entire land down under, including opening up covered skylights and completely excavating and waterproofing it all.

Tour takers learn how the house was built so quickly, and see original heating, electrical, plumbing, refrigeration, laundry and elevator systems that show how all that seamless luxury above was because of what went on below. The underground walk from the caretaker’s house where it starts to the Breakers main building, is a mini-tour in itself; the long, brick tunnel is dimly lit by replica light bulbs, and along the walls are several period photographs of The Breakers during construction, each with its own history lesion explained by your guide.

The original systems and later 20th-century adaptations show not only the immense scale and complexity of the Breakers but also the evolution of domestic technology still used in our homes today. The tour opens up these heretofore closed-off “industrial” spaces for the first time and emphasizes the technological and mechanical side of the grand Newport cottages, stressing the work of machine and humans below to make life comfortable above. You’ll see some fun things, such as the mansion’s early refrigerators, and throughout are placards telling you what part of the Breakers is directly above where you’re standing.

The names of the day are covered in the tour, such as Cornelius Vanderbilt, who had the Breakers built, and famous architect, Richard Morris Hunt, who designed it. But it also delves into the work of resident engineer, Lawrence Bauerband, who was in charge of the entire operation to run the mansion and who kept an amazingly detailed journal of daily activities and deliveries; in 1916-1017 for example, he ordered nearly a half-million pounds of coal to run the giant boilers.

Bauerband, then 26, was only at the Breakers that one year; World War I took him to France to serve his country, where he earned a Purple Heart. After the war, he returned to New York City starting a career as engineer for the city’s department stores.

The Preservation Society of Newport County runs several guided tours of its many historic holdings, but this is one of its most unique and entertaining. And one of its most popular: Reservations are strongly suggested during busy times. Also be advised, the 45-minute to one-hour tour is not handicap accessible, and comfortable footwear is recommended. Bring your camera and your questions as you go Beneath the Breakers.