A 23-year-old entrepreneur plans to spend $3 million to transform the 82-unit Penn Arts apartment building at 16th and Pennsylvania streets into 45 upscale apartments, Tracy Donhardt reports in today’s IBJ Real Estate Weekly. Chris Piazza also is planning to add a gym and sauna and will give the outside a new faÃ§ade with old-style double doors and awnings. Locally based Halstead Architects is designing the units. Piazza bought the building from JAB Real Estate Investment Group LLC in January for $1.4 million. The Penn Arts is Piazza’s seventh apartment building since launching his company, Reverie Estates, 18 months ago. Piazza, a 2005 graduate of the Indiana University Kelley School of Business at IUPUI, hopes to have an open house within five months. He also owns Village at Fall Creek, Monon Court and Essex Apartments. Piazza would not name his financial backer.