  We approach the study of sub-von Neumann algebras of the group von Neumann
algebra $L\Gamma$ for countable groups $\Gamma$ from a dynamical perspective.
It is shown that $L(\Gamma)$ admits a maximal invariant amenable subalgebra.
The notion of invariant probability measures (IRAs) on the space of
sub-algebras is introduced, analogous to the concept of Invariant Random
Subgroups. And it is shown that amenable IRAs are supported on the maximal
amenable invariant sub-algebra.
