Silicene, a newly isolated silicon allotrope with a two-dimensional(2D) honeycomb lattice structure, is predicted to have electronic properties similar to those of graphene, including the existence of signature Dirac fermions. Furthermore,the strong spin–orbit interaction of Si atoms potentially makes silicene an experimentally accessible 2D topological insulator. Since 2012, silicene films have been experimentally synthesized on Ag(111) and other substrates, motivating a burst of research on silicene. We and collaborators have employed STM investigations and first principles calculations to intensively study the structure and electronic properties of silicene films on Ag(111), including monolayer, bilayer, and multilayer silicenes, as well as hydrogenation of silicene.