Bill Mish equates himself and his staff to a football team that just won a national championship.

That is how hard they say they have worked to turn the downtown Clarion Hotel into a Doubletree by Hilton to prepare for its invitation-only grand opening tonight, said Mr. Mish, general manager of the 407 Chestnut St. hotel.

“So much effort went into this,” he said. “It has taken 2 1/2 years to get here.”

Mr. Mish said Vision Hospitality, a Chattanooga-based hotel management and development company, invested about $27 million into the Doubletree. That figure, he said, includes the purchase price and renovation costs.

Workers gutted much of the 1972-era hotel on their way to reducing 201 Clarion rooms to the 186-room Doubletree.

Prior to becoming a Clarion, the hotel was a Sheraton.

The new Doubletree’s restaurant, Eleven, will seat about 100 and serve both hotel guests and the public.

The focal point inside the full service bar, called H2O, will be a large, indoor fire pit, which burns denatured ethanol, according to Assistant General Manager Brad Witzel.

He said the company, Eco-Smart Fire, will plant two trees for every gallon of fuel the hotel buys.

“The whole hotel is surprisingly green,” he said.

The 36-year-old hotel also includes a fitness center, a virtual lounge with Wi-Fi Internet and large, high-definition, flat-screen televisions in each of the meeting rooms.

The Doubletree officially converted from a Clarion on Oct. 8.

Tonight’s celebration will include food, drink and performances by the rock and roll band Stratoblaster as well as the Mid-City South Concert Band.

Hotel officials said they mailed out about 2,500 invitations and expect about 400 to attend the celebration, which Mr. Witzel said also will serve as a fundraiser for the Creative Discovery Museum and United Way.

A silent auction will be held to sell about 70 hotel stays in cities such as Denver, Houston, Tucson and Honolulu, just to name a few, he said.

Henry Schulson, executive director of the museum, said the auction will help fund their early childhood education programs.

“It is very nice and generous for them to do this,” he said. “They are really a great neighbor for us.”