The major constituent of the nuclear envelope is the nuclear lamina. A fibrous meshwork of lamin filaments spanning underneath the nuclear membrane provides mechanical support to the nucleus. Lamins, type V intermediate filament proteins, are also involved in many other nuclear activities such as DNA repair and transcription. Recent structural studies provide new insight into how lamins assemble into ∼3.5nm thick filaments, which is in contrast with cytoplasmic intermediate filaments. The thinnest component of the cell cytoskeleton exhibits surprising mechanical properties. Here, we critically review and discuss structural and mechanical aspects of single lamin filaments.