  The most massive evolved stars (above 50 M_sun) undergo a phase of extreme
mass loss in which their evolution is reversed from a redward to a blueward
motion in the HRD. In this phase the stars are known as Luminous Blue Variables
(LBVs) and they are located in the HRD close to the Humphreys-Davidson limit.
It is far from understood what causes the strong mass loss or what triggers the
so-called giant eruptions, active events in which in a short time a large
amount of mass is ejected. Here I will present results from a larger project
devoted to better understand LBVs through studying the LBV nebulae. These
nebulae are formed as a consequence of the strong mass loss. The analysis
concentrates on the morphology and kinematics of these nebulae. Of special
concern was the frequently observed bipolar nature of the LBV nebulae.
Bipolarity seems to be a general feature and strongly constrains models of the
LBV phase and especially of the formation of the nebulae. In addition we found
outflows from LBV nebulae, the first evidence for ongoing instabilities in the
nebulae.
