The multidimensional Manhattan street networks constitute a family of digraphs
with many interesting properties, such as vertex symmetry (in fact they are Cayley
digraphs), easy routing, Hamiltonicity, and modular structure. From the known
structural properties of these digraphs, we determine their spectra, which always
contain the spectra of hypercubes. In particular, in the standard (two-dimensional)
case it is shown that their line digraph structure imposes the presence of the zero
eigenvalue with a large multiplicity
