As designers, architects and construction workers hustle to transform the former National City Bank headquarters into Marble Room Steakhouse and Raw Bar , 623 Euclid Ave., owner and manager Malisse Sinito is juggling a variety of tasks.But Sinito’s priority is to make sure the massive, three story restaurant, lounge and private party areas offer a warms and inviting environment for everyone who enters the magnificent space.“We want guests to feel welcome, above all,” Sinito says. “We don’t want it to feel intimidating or stuffy; but special, comfortable and welcoming.”The Marble Room will be housed in the banking hall of the Garfield Building, originally Guardian Bank and Trust. The space is the second largest banking hall in the world, second only to the massive L-shaped lobby of the 925 Building down the street.The new Marble Room space encompasses nearly 21,000 square feet on three floors. Sinito and her husband, Frank, founder and CEO of Millennia Companies , bought the building two years ago, as well as the adjoining Garfield Building, which was built by two of President James A. Garfield’s sons. The Sinitos also own LockKeepers in Valley View.Transforming the bank into a restaurant has been a daunting $6 million task. “The challenge has been with working with a non-restaurant space—transforming it, yet protecting and preserving its beauty,” Sinito says. “I’m proud of the amazing construction workers that are converting this historic gorgeous bank space into a new restaurant. It amazes me.”Millennia worked with Morris Nathanson Design on the interior design elements of the Marble Room.The 3,500-square-foot vault in the basement will be a private party area, complete with a pool table. In addition to the steel and reinforced concrete, three-foot-thick vault door, Millennia design and construction director Matt Solomon says the area also gives a glimpse into historic bank security measures.“Back then it was high-tech security,” he says, adding that there is a separate ventilation system and “significant” vault door combinations, among other features. “The vault has view ports to see under the vault floor, lest someone digs underneath.”Patrons to the private vault party area will also have private access through a hallway off of Vincent Avenue.When guests enter through the restaurant’s front entrance on Euclid, they will be greeted by the 8,627-square-foot main dining room, which is flanked by two, 400-square-foot cocktail areas.“They will have comfy couches and seating,” says Sinito of the lounges, adding that they plan on offering signature cocktails. “You don’t have to come in and have a steak, you can just have a glass of wine.”A long bar will line one side of the main dining room. Behind the bar will be a two-story wine cellar, accessible by staff with a switch-back stair on the side wall.A raw bar will be on the other side, featuring oysters, sushi and other items. The main menu will feature prime steaks, fish and “interesting” side dishes, says Sinito, although she says they are still working out those details.LockKeepers executive chef Alberto Leandri will head up the cuisine. “We will be hiring an executive chef for Marble Room who will open alongside chef Leandri, promises Sinito, “so chef Leandri can stay very involved at LockKeepers.”Booths will line the rest of the main dining room, with tables filling the center space. The Marble Room will seat 125.Sinito says that timely service in the large restaurant was a concern. “We had to make sure we addressed service issues so guests wouldn’t have to wait,” she explains. So the main dining area was configured with smaller spaces within the room.Overlooking the main dining room is a small balcony, which Sinito has wired for sound and may feature live entertainment.To be sure, sound was one of the major issues around creating a restaurant in the former bank space. With its cathedral ceilings and marble floors, stairs and columns, noise tends to bounce around. Sinito is addressing the acoustics with planned ivory draperies cascading from the marble pillars and sound-absorbing wall tiles fashioned from teal fabric. Wood floors will also address the issue, as will colorful and funky carpeting. “It’s fun, playful and not too serious,” Sinito says of the contemporary animal-print carpet.The 3,794-square-foot kitchen is in the rear of the space, with another lower level prep kitchen for the raw bar.A marble staircase leads to a private banquet space for up to 150 guests, while the second floor in the front of the building will house 1,789 square feet of private dining space within three rooms. One of the rooms—the former office of the bank chairman—is entirely paneled in mahogany.The third floor will house the restaurant’s administrative offices.The team will incorporate a lot of the bank's history into the overall décor, Solomon says, with old ink bottles, a document stamping machine and other banking office tools on display as design accents. He says they are also considering displaying the original, hand-drafted floor plans.Both Sinito and Solomon say they are in the middle of the entire project—the part that is always the hardest. “Getting decisions made as conditions are revealed are expected surprises,” Solomon says.But Sinito says the work is worth it. “It’s still early on and the fun is yet to start,” she says. “I think the highlight will be when the vision starts to become a reality.”