Consider it a textbook example of how to transform a dilapidated eyesore into a potential community jewel.

For nearly a quarter-century, the former South Hills High School in Mt. Washington slowly deteriorated while various redevelopment proposals were about as successful as the initial Hindenburg launch.

As recently as 18 months ago, the enormous 155,000-square foot building occupying an entire city block at the corner of Ruth and Eureka streets stood empty and decaying.

Surrounded by an imposing chain link fence, the old school appeared as though it never would be anything more than a refuge for birds seeking shelter through the holes in the roof.

Since then, the scene has changed dramatically.

“We’ve come a long way,” Victor Rodriguez said Tuesday, standing in the vicinity of where the principal’s office used to be. “I think this is pretty monumental in terms of what we’ve accomplished.”

Rodriguez is senior vice president of a.m. Rodriguez Associates, which purchased the building from the city’s Urban Redevelopment Authority two years ago for $1. Given the structure’s condition at the time, Rodriguez might have overpaid for it.

But following a $23 million makeover that included $10 million in public money, the structure will reopen in about six weeks as the South Hills Retirement Residence.

The place is proving popular among the senior crowd even before the first tenants move in. As contractors scurry to apply the finishing touches, 42 of the building’s 106 units have been leased.

Rodriguez yesterday provided me a tour of the building, the inside of which looks virtually nothing like it did when the Class of ’86 closed the school for good.

Although some of the original hardwood and ornate metal railings were incorporated into the interior design, it’s unlikely the 2,200 members of the school’s alumni association would recognize the place.

That’s a good thing.

Rodriguez removed several unsalvageable portions of the former school, including the auditorium and the swimming pool, while adding amenities the 94-year-old building desperately needed — elevators and air conditioning.

In addition, a portion of the building is expected to house medical offices, which should further increase foot traffic in what had become a desolate neighborhood. An early childhood development center also might occupy some space.

“What we’re striving for here is something community-changing,” Rodriguez said.

Joshua “J.T.” Smith, board president of the Mt. Washington Community Development Corp., lives about two blocks away and is thrilled with how the place looks.

“For years, that building created a real negative mood with all of that prison-style fencing around it,” he said. “It’s great to walk by now and see something vibrant and alive, with the new trees and the clean sidewalks. This is going to alter the mentality of the whole neighborhood.”

Again, it’s a textbook example of transformation.

For an old school, what could be more appropriate?