This project lies at the interface of active matter and out-of-equilibrium statistical physics. Cellular tissues are a particularly rich example of active systems: cells consume energy, interact mechanically and collectively generate stresses. When cells are elongated, they can also display a collective orientational order analogous to that of nematic liquid crystals. The overall goal is to understand how microscopic cell–cell interactions give rise to the mechanical properties and collective organisation observed at the tissue scale. The novelty of the project is to study cellular multilayers as living lamellar liquid crystals: layered structures that can deform, flow and actively produce forces. The work combines experiments, development of analysis tools and theoretical modelling, in a strongly interdisciplinary approach at the crossroads of active-matter physics, biophysics and materials science.