Crossing the threshold into the grand entry hall of the Mediterranean-style house in Beverly Hills is like stepping into a time capsule.

Up for sale for the first time since it was built in 1925 for its original owners, the elegantly understated house — listed at $5.5 million — doesn’t ooze wealth so much as good taste and a 1920s practicality.

“There was a mind-set among the rich back then,” said listing agent Bret Parsons, the founder and managing director of Aaroe Architectural. “You do it once, do it right and that’s it.”

If it seems that a house built when Calvin Coolidge was president has been a long time coming on the market, it is. Seven years was the average amount of time for a homeowner to hold onto a house before selling it last year, according to the California Assn. of Realtors, up from five years before the housing downturn.

Nationwide, slightly more than 15% of owners have been in their houses at least 30 years, according to the Census Bureau.

A California bungalow built in 1912 appeared on the Multiple Listing Service in January for the first time, but agent Jimmy Ishoo said the Westlake-area house had been reworked and updated over the years.

What makes the Beverly Hills house a rarity is how much of the home is unchanged.

Named Winter House for its owners, insurance executive Frank Winter and his wife, Florence, the 4,748-square-foot residence remained the home of their daughter, Frances, until her death late last year at 101.

Frances Winter never married or established her own address, choosing instead to entertain in the two-story home of her parents and live out her years still sleeping in her childhood bedroom. When she could no longer handle the stairs, a bed was moved downstairs.

In contrast to the towering ceilings in the central entry hall, the adjacent library has a more human scale. Wood bookshelves, detailed in the original blueprints, line either side of the barrel-ceilinged room, and a fireplace with a tile-surround is flanked by tall windows.

Several shelves converted to a catalog system for phonograph records still contain 78s bearing the titles of waltzes and fox trots. At the time the house was built, 78 rpm was becoming the standard rotation speed for records and the Victor Orthophonic Victrola was introduced to consumers.

Next to the den sits the dining room. On the floor near the head of the table is a foot button hidden beneath carpet that, when pressed, buzzes loudly in the kitchen — signaling the help that it is time for the next course or for plates to be cleared. Another floor buzzer is in the morning room, where the family would take breakfast. Both still work.

Entered through the butler’s pantry, the kitchen is a utilitarian affair with high ceilings and floor-to-ceiling cupboards.

This is the sensible kitchen of owners who needn’t spend much, if any, time in the room. Hired help prepared the meals and cleaned up. A dumbwaiter carried trays of food up to the bedrooms and office on the second floor.

An antique Universal range and oven, with built-to-match salt-and-pepper shakers and a timer on a small shelf, still works. This model is at least 80 years old, according to the experts at Antique Stove Heaven in Harbor City.

A mirror hangs above the kitchen sink: odd placement to modern eyes but extremely practical in its day.

“When a housekeeper is working there, she can see what is going on behind,” Parsons said. “She had to keep her eye on the door to the dining room at all times.”

Transom windows that provide natural air conditioning sit atop the doors off the kitchen that open to a back room used for deliveries and a laundry and ironing room. A back staircase leads to a staff bedroom with bathroom.

The large living room was cooled in the summer by casement windows that crank open.