The owners of the Garden City Hotel are starting to unveil a makeover that could cost up to $40 million.

The iconic property, Long Island's oldest operating luxury hotel, opened its first floor of renovated rooms for guest bookings last week and will begin showing its remodeled meeting spaces to potential corporate clients and event planners Thursday.

Fortuna Realty Group, which bought the hotel for $42 million from the Nelkin family in 2012, has committed at least $26 million on reconstruction work that includes a new restaurant -- Polo Steakhouse -- a guest room redesign and an upgrade to the front facade, said the hotel's general manager, J. Grady Colin.

Fortuna founder Morris Moinian has taken a "money is no object" perspective on the renovation costs, which could rise to $40 million, said Colin, who is also a Fortuna vice president.

"Mr. Moinian always regarded the Garden City Hotel as one of the foremost prestige hotels on the East Coast, and wanted it to be the jewel of his collection," he said.

After Christmas, all 272 rooms and 16 suites at the hotel were closed and gutted. The redesign gives them a sleek and modern feel, a departure from the previous classic traditional style with brocades and tasseled curtains. All the rooms are scheduled to be completed by May. The hotel's public and event spaces were redone last spring.

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Room rates could rise between $80 and $300 per night, reaching $229 to more than $700, after the renovation, Colin said. The hotel also wants to attract more corporate clients and events to improve occupancy on weekdays. It has converted a larger portion of its rooms to single occupancy.

The upgrades at the hotel are long overdue, said Mike Johnston, a principal at Plainview-based Concorde Hotel Group, and will help put life back into the local hotel industry. "Their competitors will have to step it up a notch . . . It's very good for the guests."

Luxury hotels, which were hit hard during the recession, have rebounded strongly, said Adam Weissenberg, a hospitality and leisure industry analyst at Deloitte & Touche.

Nationwide, occupancy and revenue per available room, or "revpar," at luxury hotels are both on the upswing. In 2013, occupancy rose 1.8 percent from a year earlier, and revpar increased 7.6 percent, according to industry research firm STR Global.

The reconstruction has been approved for up to $2.6 million in breaks on sales and mortgage recording taxes from the Nassau County Industrial Development Agency, contingent on Fortuna's meeting with local unions. The developer's use of workers from out of state drew fire during the approval process for the tax breaks.