While the fabled aerie atop Rockefeller Center is long gone, this sister show has proven especially durable. Eighteen years later, it is paying a five-performance visit to 54 Below through Aug. 31.

Not only is the act durable, it provides high entertainment. Most family acts are not only complementary but self-supporting; the combined talent is stronger than the individuals. The Callaway girls, though, are independent. Either of them, alone, is fully capable of providing a full night's entertainment. In Sibling Revelry, we get equally expert solo segments tied together and punctuated by delectable two-part sister stuff. It's sort of a mutual admiration society in which "anything you can do, I can do better."

Both Callaways have been entertaining New York audiences for years. Liz is the Broadway baby. A survivor of the original ill-fated Merrily We Roll Along in 1981, she garnered a well-deserved Tony nomination in 1983 for Baby. This was followed by the original Broadway production of Miss Saigon and a five-year-long stint as a replacement Grizabella in Cats. Ann, too, has a Tony nomination for her one Broadway appearance, in the 1999 musical Swing!, but her career has been spent in cabarets and recording studios, and writing songs, including "The Nanny Named Fran" for the '90s sitcom "The Nanny." This was recorded by the sisters together, and they reprise it in Sibling Revelry.

	Ann Hampton Callaway

The evening gets off to a strong start with the girls duetting their way through "It's Today," "The Sweetest Sounds" and "I Can See It." (This last, from Harvey Schmidt and Tom Jones' The Fantasticks, features a section of dueling vocalizing.) After typical "sibling rivalry" patter, Ann takes the stage with two knockout solos. First, she swings her way through the old Tommy Dorsey hit, "Rhythm in My Nursery Rhymes." This is followed by a stunning rendition of "Old Friend" (from Gretchen Cryer and Nancy Ford's I'm Getting My Act Together and Taking It on the Road) framed with the old standard, "My Buddy."

Next comes an aggressively sisterly version of Cole Porter's "Friendship," followed by Liz's two solos: a "Meadowlark" that soars and an exquisite "My Heart Is So Full of You." An a cappella duet of the Legrand-Bergman "You Must Believe in Spring" leads to what the sisters call their "Huge Medley," a 13-minute jaunt encompassing bits and pieces of 18 songs. (The most ridiculously delightful moment of the medley, and the evening, comes when Ann spits her way through West Side Story's "A Boy Like That," with Liz providing an earsplitting soprano and rolling her rrrrs through "I Have a Love.") The act ends with an especially lovely rendition of Stephen Sondheim's "Our Time" and Frank Loesser's "Brotherhood of Man." In keeping with the family connection, the act is smoothly directed by Dan Foster (husband to Liz). Strong support is offered throughout by musical director Alex Rybeck, who has been with Sibling Revelry since its inception, with Jered Egan on bass and Ron Tierno on drums.

While the Callaways come out dressed identically, in black tuxes with white shirts and diamondish buttons, they don't look or sound or even sing like sisters. Think of them like Mandy and Patti or Gwen and Chita, or for that matter like a soulful flute paired with a woodsy bassoon. The results make for top-notch cabaret, still, after 18 years. Catch them this week at 54 Below or wherever they decide to do it next.