The Pittsburgh History & Landmarks Foundation is tackling another building rescue project in Market Square, with the aim to further a transformation already under way in the historic Downtown public square.The South Side preservationist organization announced today it will take on restoration of the Thompson Building, a three-story structure adjacent to a trio of vacant buildings where it is spending about $2.5 million to convert into a mixed use complex known as Market at Fifth.

Acquisition of the building will enable the foundation to expand its complex into that structure.

Plans for 439 Market St., 441 Market St., and 130 Fifth Ave. include a ground-level restaurant or retail store, seven upper-floor apartments and a rooftop garden.

In addition, the foundation also announced it was given an “easement in perpetuity that will protect the architectural quality of the Buhl Building, another structure on Fifth Avenue near Market Square.As reported, eight new shops have moved in — or will in the coming months — further rejuvenating the 224-year-old square.

Businesses there have credited an increased police presence to fight crime, reduce panhandling and efforts to clean up the city’s streets.

More recently, new programs have been introduced, such as the Pittsburgh Downtown Partnership’s Paris to Pittsburgh program that is providing matching grants to help restaurants and other merchants renovate their buildings and expand their operations onto sidewalks — similar to venues popular with tourists in the French capital.