"Hail Mary" to the city, you're a virgin
Play on the virginal status of Mary, the mother of Jesus, who was born without sin (with the suggestion that moving to the city will corrupt you); Jay-Z “hails” (celebrates) the city’s darker elements.
(One could also interpret “Hail Mary” as a last ditch attempt at success (i.e. a Hail Mary pass in football). In other words, a “Hail Mary to the city” could refer to the theme of coming to New York as an attempt for success despite the danger and risk that lies there… which leads to the next line.
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