The Richthofen Castle, an iconic relic of Denver history, is under contract for sale.

The 125-year-old turreted mansion in east Denver’s Montclair neighborhood is scheduled to change hands next month at a price of close to $3.75 million.

If the deal closes, it will mark the end of 14 years of on-and-off-again efforts to sell the 35-room estate that was built by the uncle of Baron Manfred von Richthofen, better known as the Red Baron flying ace of World War I.

Baron Walter von Richthofen, a Prussian immigrant turned Colorado mining baron, conceived the idea for the limestone castle in the 1870s and finished it in 1887. He planned — unsuccessfully, as it turned out — to have it serve as the catalyst for an upscale residential development in what was then a dusty prairie five miles east of downtown Denver.

Several Victorian-era mansions were built nearby, but most of the area remained undeveloped until decades later.

The castle at 7020 E. 12th Ave. had a succession of owners in the 1900s, culminating in 1984 when it was purchased by current residents Jerry and Esther Priddy.

“It’s definitely one of a kind. There’s nothing like it,” said listing agent Casey Miller of Fuller Sotheby’s International Realty.

The 15,000-square-foot gated mansion has eight bedrooms, seven bathrooms, five fireplaces, a bar, drawing room, library, servants quarters, butlers pantry and billiards room.

Miller declined to identify the buyers, who are Denverites. He said the contracted price is “close to” the asking price of $3.75 million.

The Priddys had offered to sell the castle’s elaborate furnishings for an additional $2.2 million, but Miller said the buyers have agreed to purchase only some of the items individually.

Jerry Priddy had amassed what he described as the largest known collection of Red Baron memorabilia. The collection was displayed in the castle’s basement until he sold it.

Steve Raabe: 303-954-1948 or sraabe@denverpost.com