  We study the problem of planning paths for a team of robots for visually
monitoring an environment. Our work is motivated by surveillance and persistent
monitoring applications. We are given a set of target points in a polygonal
environment that must be monitored using robots with cameras. The goal is to
compute paths for all robots such that every target is visible from at least
one path. In its general form, this problem is NP-hard as it generalizes the
Art Gallery Problem and the Watchman Route Problem. We study two versions: (i)
a geometric version in \emph{street polygons} for which we give a polynomial
time $4$--approximation algorithm; and (ii) a general version for which we
present a practical solution that finds the optimal solution in possibly
exponential time. In addition to theoretical proofs, we also present results
from simulation studies.
