William Penn envisioned Philadelphia, the city he established in 1682, as a “greene Country Towne” along the Delaware River. Equally verdant was composer Romeo Cascarino’s vision of “William Penn,” the opera, which he crafted over a quarter century, from 1950 to 1975. The completed work was first heard at Philadelphia’s Academy of Music in 1982, to coincide with the 300th anniversary of the city’s founding.

I’ll be presenting Cascarino’s magnum opus tomorrow morning on WPRB, as I sit in for Sandy Steiglitz on “Sunday Morning Opera.” Metropolitan Opera singer bass-baritone John Cheek will sing the title role, and Christopher Macatsoris will conduct the Philadelphia Singers and the Chamber Orchestra of Philadelphia.

I will be joined in the studio by a very special guest: Dolores Cascarino, the composer’s widow, who created the role of Gulielma (as Dolores Ferraro), Penn’s first wife. She will offer insights into the opera and its creator, and share her memories of that premiere run of performances. The program will also include private recordings of some of the composer’s other works, with a special focus on his writing for voice.

I hope you’ll join me for this one-of-a-kind broadcast of a first-rate, virtually unknown American opera, in a recording which is not commercially available, with valuable insights from the composer’s closest confidante, who sang in the work’s first performance.

It all comes your way tomorrow, on “Sunday Morning Opera,” from 7 to 10 a.m. EST, on WPRB 103.3 FM and at wprb.com.

Tune in early to enjoy a pre-show treat, the world premiere broadcast of collaborations with pianist Richard Rome, a producer in the field of commercial music, in arrangements made by Cascarino, who will conduct the orchestra in a program of works on celestial themes. The album, recorded at Cinecittà studios, outside Rome, was never released. Musicians for the sessions were assembled from performers who were heard on the soundtracks of Italian films of the era, who recorded for RCA Italia, and who played at La Scala Milan. The airing of this music, great background for your morning coffee, will begin around 6:30 a.m.

PHOTO: John Cheek as William Penn, with my guest, soprano Dolores Cascarino (née Ferraro), as Gulielma