  The exact nature of the lowest $K^\pi =2_\gamma ^+$ rotational bands in all
deformed nuclei remains obscure. Traditionally they are assumed to be
collective vibrations of the nuclear shape in the $\gamma$ degree of freedom
perpendicular to the nuclear symmetry axis. Very few such $\gamma$-bands have
been traced past the usual back-bending rotational alignments of high-j
nucleons. We have investigated the structure of positive-parity bands in the
N=90 nucleus 156Dy, using the 148Nd(12C,4n)156Dy reaction at 65 MeV, observing
the resulting ${\gamma}$-ray transitions with the Gammasphere array. The even-
and odd-spin members of the $K^\pi =2_\gamma^+$ $\gamma$-band are observed to
32+ and 31+ respectively. This rotational band faithfully tracks the
ground-state configuration to the highest spins. The members of a possible
$\gamma$-vibration built on the aligned yrast S-band are observed to spins 28+
and 27+. An even-spin positive-parity band, observed to spin 24+, is a
candidate for an aligned S-band built on the seniority-zero configuration of
the $0_2^+$ state at 676 keV. The crossing of this band with the $0_2^+$ band
is at $\hbar\omega$= 0.28(1) MeV and is consistent with the configuration of
the $0_2^+$ band not producing any blocking of the monopole pairing.
