The former Gulf Oil Building, an iconic art deco tower on the downtown skyline, will undergo a major renovation by a well-known Houston development company that hopes it will renew interest in a block of Main Street.

Midway, the Houston developer responsible for CityCentre and Green Street, and the building owner, Lionstone Investments, announced plans Thursday to rebrand and renovate the 37-story tower, now anchored by JPMorgan Chase at 712 Main. The developers will combine it with the adjacent historic building at 708 Main.

Proposed renovations call for the ground-level connection of the two buildings, updated interior and new street-level restaurant and retail spaces.

"It's one of the most iconic and important properties in Houston," Midway CEO Jonathan Brinsden said. "Our job was to figure out, How do we reinvent the building as an icon once again and make it into something that is really unique and a differentiated experience for potential tenants? We are bringing it back to life to make it a premier building downtown."

The building commissioned by Jesse H. Jones in 1927 was the tallest in Houston until 1963. It is significant today for its art deco exterior and an interior that features terrazzo floors, a dramatic ceiling and gold-leafed touches typical of the era throughout, said David Bush, president of Preservation Houston.

Bush said he would be concerned if any of the historic features were tampered with. The building is a state landmark and holds a place on the National Register of Historic Places.

"It's a classic art deco skyscraper," Bush said. "It is one of the most significant art deco interiors at least in the state, if not a bigger region. It's amazing that over the years it hasn't been significantly changed."

The two buildings combined are 84 percent leased, yet this announcement comes at a time as downtown is struggling with floors of vacant space available in its buildings thanks to the energy downturn. Downtown boosters point to the project as the latest in a series of positive moves that promise more life in the area. A big piece of Midway's plan is to bring more retail and restaurants to the street level.

"They are trying to figure out how to make it more 'with it,' " Central Houston president Bob Eury said. "One of the things they will be aiming for is to create an environment that works longer than the 8-to-5 environment. I think that's been the real interest in this whole area at the core of downtown."

Eury noted other projects along Main Street in recent years, including the Hines office tower, the renovation of the JW Marriott and plans for the Esperson building to create co-working spaces.

This will be the first historic building project Midway will take on, Brins-den said. The renovations will begin in June and are expected to be completed in early 2017. He said it is critical to also develop the 708 Main building to make sure to control and curate the ground-floor retail.

Brinsden said the grand lobby, which has so many of the historic details and finishes, will remain intact. Some details hidden by sheetrock over the years were exposed during the preliminary renovation process. That included some of the art deco touches, metal handrails, terrazo floors and historic art scenes.

JPMorgan Chase will remain the primary tenant, occupying nearly 452,000 square feet of office space in the building as well as a 29,000-square-foot banking center on the ground floor. The bank has occupied the building since 1929.

"712 Main tells the story of Houston's rise as an economic powerhouse," said Greg Hassell, executive director of communications for JPMorgan Chase. The redevelopment plans take over some of the ground-floor retail space from Chase to make way for new retail and restaurants.

Meanwhile, the downtown office market is feeling some strain. The Houston region has about 8.4 million square feet in sublease space available, and of that, there is 6.5 million of full-floor or more available, said Robert Kramp, director of research and analysis at CBRE for Texas and Oklahoma markets. Downtown and the Energy Corridor are suffering the most. In downtown, there is about 1.9 million square feet of space and of that, 1.3 million is full-floor.

He said during the recent boom from 2011 to 2015, many new high-class offices were built that will help Houston in the long-term. He said older buildings need to update their systems to keep up.

"Houston will be very competitive," he said. "The newly built will trump the existing space options out there that are dated."