  In the tensionless limit of string theory on flat background all the massive
tower of states gets squeezed to a common zero mass level and the free theory
is described by an infinite amount of massless free fields with arbitrary
integer high spin. We notice that in this situation the very notion of critical
dimension gets lost, the apparency of infinite global symmetries takes place,
and the closed tensionless string can be realized as a constrained subsystem of
the open one in a natural way. Moreover, we study the tensionless limit of the
Witten's cubic sting field theory and find that the theory in such a limit can
be represented as an infinite set of free arbitrary higher spin excitations
plus an interacting sector involving their zero-modes only.
