A $100 million, 13-story office building soon will replace a downtown block on F Street where women once browsed for fashionable clothes in Jelleff's, secretaries grabbed $1.15 hamburgers at Case's Sandwich Shop and teen-agers flocked to I. Miller's for the popular shoes called "Nineteens" while their mothers preferred Chandler's and DeYoung for footwear.

The office building that will replace the two- and three-story stores on the south side of F between 12th and 13th streets NW is the most recent example of the slow but steady urban renewal of downtown that has been fueled largely by private dollars.

F Street, the heart of downtown Washington, was once the shopping mecca for the area, then an ugly stepsister to suburban malls. But a combination of the refurbishing of Pennsylvania Avenue, two blocks to the south, and the coming to downtown of new office buildings has made F Street like a diamond in the rough that is now being recut and polished.

Mortimer Lebowitz, owner of Morton's, the last store to close on the doomed 1200 block, remembers the old F Street. "When I first came to town in 1935, it was a block that had very fine stores. My wife tells me when she was a girl, Jelleff's was really a top-notch store," he said.

Elliot Kapstein, manager of Morton's at 1220 F Street NW, dislikes the transformation of the downtown from a cluster of small shops and empty storefronts to a hub of high finance and boutiques.

"The city's being decimated," said Kapstein as he supervised Morton's "going out of business" sale last week.

"Morton's is a store for the people. It always has been," Kapstein said.

"No longer will downtown be a place for the so-called common folk. There's no popular store in the city. Now this will be a big building full of lawyers," he scoffed.

The prestigious Washington law firm of Hogan & Hartson has leased 50 percent of the new building, which was designed by the firm of world-famous architect I.M. Pei for Houston developer Gerald Hines. Construction is scheduled to begin this spring as the block is demolished.

With the move, Hogan & Hartson, now located at 815 Connecticut Ave. NW, will join several other major law firms in an exodus from the west side of Connecticut Avenue to the old downtown.

The Shops at National Place, a collection of glitzy specialty stores, opened in the adjacent 1300 block of F Street last year. Their counterparts are expected to occupy the street level of the new building as upscale retailers rediscover a street they once snubbed.

Fifteen stores on F, 12th and 13th streets have been displaced by the construction. About three closed permanently, and seven have moved to other locations in downtown, including DeYoung Shoes, which plans to open in The Shops, plus Storm's Shoes and Case's Sandwich Shop. The remainder moved to other parts of the city or have only suburban outlets.

Morton's officials decided to open in the Brentwood Shopping Center at 1311 Rhode Island Ave. NE, leaving the downtown area for the first time in the company's 50-year history.

Charles Rosenberg, manager of Storm's Shoes, which has been at 520 12th Street NW for nearly 50 years, found a new location downtown at 1219 E St. NW.

Rosenberg said that with the increased foot traffic generated by The Shops and the Pavilion at the Old Post Office Building, his business is successful, but that it is "just a question of when" soaring rents will force him out of downtown.

Edward Case, 31, grew up close by in his parents' restaurant, Case's Sandwich Shop, at 526 12th St. NW. "When I first was going in there, black people weren't even allowed to sit at the front counter," Case remembered.

But by the early 1960s, Case said, the shop was fully integrated. Customers would crowd into the tiny diner, which is big enough for only a counter and three booths, as "Casey" Case worked the grill, juggling as many as 25 lunch orders in his head. Diners filled up on cheap meals: a hot dog for 70 cents, a spaghetti dinner for $1.90.

"F Street was a nice place for the small-business person," Edward Case said. "My dad didn't leave me much. But he lived well. He bought a new Cadillac every year. He lived a comfortable life for a small-business man."

Casey Case died in 1983, and last year his son moved Case's to 512 Ninth St. NW because of the impending new office building. "I just wish he could have seen the new place, because it's really pretty," Case said, recalling his father.

In the back of Morton's building it is possible to glimpse a vestige of F Street's classy past -- a paneled, stained-glass window depicting scenes of trade in an undetermined period of history. In one of the many scenes a merchant displays a bolt of fabric; in another, a noblewoman tries on a dress.

The window, according to Lebowitz, was comissioned by Frank A. Jelleff in 1925 for $2,500. The artist, Nicola D'Ascenzo, an Italian immigrant, designed stained-glass windows for Healy Hall at Georgetown University, the Folger Shakespeare Library and the Washington Cathedral, as well as for many local churches. Lebowitz said he plans to donate the window panels to the Smithsonian Institution's division of ceramics and glass.

Jelleff's closed in 1972, and Lebowitz purchased the building and moved his store from Seventh Street in the eastern end of downtown, where subway construction was crimping his sales, he said.

"I never in my wildest dreams thought our Seventh Street store would occupy Jelleff's," Lebowitz said. "We were selling merchandise to working-level people, and Jelleff's was selling to comfortably situated people."

The 1200 block of F Street was also once the address of such shops as Urdong's, a now-defunct women's clothing store; Chandler Shoes, now with outlets only in the suburbs, and I. Miller Shoes, which closed in 1971 because of the death of a Washington fashion phenomenon -- the "Nineteen" shoe.

The I. Miller store sold nearly $1 million worth of the Nineteens, mostly to black high school girls in the District from the mid-'50s to the mid-'60s when the low-heeled, buckled-strapped, slingshot shoes became a fashon legend.

"It was a great rage," Rosenberg recalled. "Other shoe stores tried to duplicate it, but the original one was from I. Miller. They cost $20 -- high-priced in those days. Everybody had to have them."

Alice Hasner, who managed Dana Robins' F Street store, a women's dress shop, until it closed a year ago because of the new construction, said, "It's very, very sad that the people who used to shop here all their lives are being priced out of downtown. We're exchanging people for big dollars. That's what it amounts to."

And of those customers, she said, "I'm sure they will be cast aside. It's typical how we operate in this city in the name of progress."