  The bosonic string in D dimensional Minkowski space-time is quantized in
static gauge. It is shown that the system can be described by D-1 massless free
fields constrained on the surface L_m = 0, for m \neq 0, where L_m are the
generators of conformal transformations. The free fields are quantized and the
physical states are selected by the conditions L_m|phys>=0, for m>0. The
Poincar\'e group generators on the physical Hilbert space are constructed and
the critical dimension D=26 is recovered from the commutation relations of the
boost operators. The equivalence with the covariant quantization is
established. A possible generalization to the AdS string dynamics is discussed.
