N.Y.C. Admin. Code § 27-2041: § 27-2041 Peepholes.

In every dwelling the owner shall provide and maintain a peephole in the entrance door of each dwelling unit. Such peephole shall be located, as prescribed by the department, in such a place that the person in each dwelling unit may view from the inside any person immediately outside the entrance door. However, such peephole need not be installed in any tenant-occupied one- or two-family home where it is possible to see from the inside any person immediately outside the entrance door. This section shall not apply to hotels, apartment hotels, college or school dormitories, or owner-occupied dwelling units in one- and two-family homes.