The Del Taco building, whose future still remains very much in doubt, does not owe its distinctive shape and swooping, saucer-like roof to its recent taco-dealing tenants. More than 40 years ago, architect Richard Henmi designed the building and its hyperbolic-parabaloid-shaped roof as a Phillips 66 gas station. The roof protected gas pumpers as they stood outside filling up cars. Only much more recently had the building, at Grand Boulevard and Forest Park Avenue, been repurposed to dispense food instead of gas.

The Del Taco/Phillips 66 building is just one of many St. Louis buildings that have been adapted, repurposed, rehabbed or redesigned from their original uses, thanks in part to a state historic tax credit.

"There are a lot of buildings in St. Louis like the Del Taco/Phillips 66 building. Buildings are originally constructed for pretty much a single purpose and then over the course of time, new uses need to be found for them or they are demolished or abandoned," said Ryan Reed, a preservation specialist at the Landmarks Association of St. Louis.

Healing City hospital

One of the area's most ambitious rehab projects in progress has been the redevelopment of the old St. Louis City Hospital, on Lafayette Avenue at 14th Street. Public hospitals have sat on the site since 1848, but the current buildings date back to the late 1890s. The hospital was in operation until 1987, when the buildings were abandoned. Slated to be destroyed in 2001, City Hospital was placed on the National Historic Registered and eventually saved from the wrecking ball.

It was at this point that Chris Goodson, co-founder of the Gilded Age, stepped into the picture. Goodson and his company have developed and redeveloped $200 million worth of properties in St. Louis mostly around Lafayette Square.

"City hospital was just abandoned buildings. They had been that way for over 25 years. We purchased that whole site and put together the development plan," Goodson said.

That plan first involved developing 108 condominiums; they have already been built and sold. After the condos Goodson began building retail space, which will be completed by the end of 2011. By mid 2013, the development is scheduled to have office space as well as a grocery store.

The redevelopment will also repurpose the hospital's old power plant and its towering smokestack into the Midwest's largest climbing gym. "We've been able to incorporate the smokestack into the development of the climbing and bouldering gym. This 80-foot high space where all the power equipment was will now be an exciting gym," Goodson said.

All aboard for rehab

With all the work to retrofit and update old buildings, Goodson says that it is usually less expensive to build a new building on a clean site than to rehab an existing building. But the benefits of rehabbing are in maintaining the building's character itself.

"We couldn't afford to build this building ... Back then labor was cheap, material was expensive. Now it's flipped. Because of that, back then they could build this building with hand-laid, 20-inch thick stone walls. No one is going to build like that again."

That's Michael Blaes, of Blaes Architects, talking about his firm's current office located at 643 Glen Road, in the old Tuxedo Park commuter train station in Webster Groves. The building was constructed in 1890, and its history follows a similar storyline to Goodson's much larger City Hospital. After commuter rail service ended in 1961, the building was used for storage and maintenance until 1980 when it was given to Webster Groves to save it from destruction. It sat unused for almost another two decades until Blaes convinced the city to let him rehab it and use it as his firm's offices.

Blaes lists the different tasks he has had to do to make the building inhabitable: "Cleaned the place out. New plumbing. New bathroom. New heating and cooling. Put in a gas coal fire set in the fireplace. Refinished the fireplace. Refinished the floors. Painted the whole space. Repaired windows and doors. Rebuilt some doors. Cleaned stone on the outside. Repainted outside, replaced the roof."

Blaes grew up blocks from the train station in a house his grandfather built. His grandfather daily used the train station and rode the commuter line. "I've always had a fascination with older buildings. And that's the type of work we do. Mostly older homes," Blaes said.

Museum, sweet museum

The first conversions in the area occurred in the early 20th century when old houses were adapted into house museums for preservation. Some of these very early houses were converted into museums. The Eugene Field House and Toy Museum, 634 South Broadway, built in 1848, was opened Dec. 18, 1936 as the first historic house museum in St. Louis. The Taille de Noyer House, 1896 S. New Florissant Road, dates back to 1790. It was moved from its original site in 1960 to become the home of the Florissant Valley Historical Society.

"It used to be that people only thought of a handful of buildings as historic" in a given community, said Esley Hamilton, St. Louis County's Historic Buildings Commission preservation specialist and lecturer at Washington University's College of Architecture.

Those buildings included only the oldest houses and civic buildings, mostly antebellum structures. But as more and more buildings have been developed, built and torn down, people have expanded their sense of what a historic building is. "Today, post-World-War-II buildings are the focus of preservation efforts in many communities. These buildings that 25 years ago people wouldn't have thought were significant in any way," Hamilton said.

Hamilton explained that architects and developers realized that St. Louis could not maintain every historic building by turning it into a museum. Instead, developers had to find new economic uses to support the buildings they were redeveloping.

The county's Historic Buildings Commission has honored buildings that have exhibited outstanding adaptive reuse. It has recognized more than 60 buildings since 1982.

Unpolished gems are everywhere

Which brings us back to buildings like Blaes Architects' office, which was honored in 2011 by the commission, and Goodson's redeveloped City Hospital. Those two developments represent redevelopments on both ends of the sprectrum — the largest and smallest scales — but developers are rehabbing buildings of all shapes and sizes.

One of the most unique buildings Goodson has redeveloped was an old 1878 Presbyterian Church in Lafayette Square. It was turned into nine condominiums. "Where the pipe organ was, we turned into one huge room with 35-foot ceilings. Behind the pipe organ where the guts used to be is the kitchen. So you walk through the door and you have these pipe organ pipes above," Goodson explained.

Developer Jason Deem and his team took two interconnected buildings at Cherokee Street and Jefferson Avenue and turned the complex into a shared coworking space called Nebula Coworking. The earliest of the two buildings was built in the late 1800s. The second building was erected in the 1920s.

"What's interesting in a building this old is to try to figure out all the different things that have been altered and what is original. What we tried to do is get back as much as possible to the original," Deem said.

The second floor of the building was a probation office and the first floor had sat empty when Deem purchased it. "We found a really interesting safe in the basement. We still haven't opened it. There's all kinds of artifacts from days passed," Deem said.

Deem echoed Mike Blaes' opinion that the greatest benefit to redevelopment is saving the material and workmanship of the old building itself. But he also noted that redevelopment projects require greater creativity within the constraints of the existing building.

"It really forces the developer to be creative with how you design the space while trying to preserve as much of the original structure as possible, too. You don't just get to design a floor plan from scratch," Deem said.

Historic tax credit keeps past alive

These developers all say that the importance of the state tax credit cannot be overstated. "I can't stress enough how important the tax credit has been to this economy of Missouri over the last decade," St. Louis County's Hamilton said. Talking about the City Hospital's climbing gym, Goodson said, "Without the tax credit program, we would have had to leave that building abandoned."

Deem said, "The tax credits are critically important. A lot of the development that has happened around Cherokee Street would not have happened without tax credits. The credits are just enough to tip the scales and make it worth doing a project."

Even architect Richard Henmi, the original architect of the Del Taco/Phillips 66 building, has in more recent years designed a number of redevelopment projects, mostly for hotels. He designed the Coronado Hotel's conversion into apartments. He also designed the transformation of the old J.C. Penney downtown distribution warehouse into the new Sheraton Hotel. To provide more windows and light to the new hotel rooms and condominiums, Henmi cut out a large, eight-story atrium in the middle of that building.

But his most unique redevelopment has to be the current Hilton Hotel at Walnut and South Broadway. That development is two tall towers connected by a low-sitting building. That low-sitting building was originally the Spanish Pavilion at the 1967 New York Expo. It was the architectural gem of the Expo, and then-mayor Al Cervantes lobbied strongly to have the pavilion moved to St. Louis to be used as a civic center.

That civic center never could survive economically, so a hotel developer asked Henmi to redesign it into a hotel. "We wanted to be sure not to disturb the pavilion needlessly. We wanted to preserve the appearance of the building. So we carefully dropped one tower into a court yard that happened to be in the middle of the pavilion," Henmi said. "The design really worked out well."

St. Louis has many well-built, old buildings just waiting to be turned into new apartments, office spaces, condominiums, and retail outlets. "You can try to come as close as you can to the workmanship by using salvaged material, but that's just purchasing pieces of an existing building," Deem said. "You can't even come close in a building built yesterday to the level of character that these old St. Louis buildings have."