appropriate symmetries are maintained. An important example is the quantum spin Hall insulator [@Hasan2010], protected by time reversal symmetry, whose edge physics may be used in spintronics [@Ilan2014; @Wu2011; @Ojeda2012] and in the creation of topologically protected qubits in the form of Majorana fermions [@FuKane2008]. Partially motivated by the search for other exotic boundary phenomena, the field has developed rapidly: The classification table of weakly interacting topological phases of electrons given various symmetries has been established [@TenFold2010] in what can be seen as a modern revival of band structure theory. Furthermore, various topological electronic phases have been realized [@Hasan2010; @Qi2011]. Turning to bosons, a difficulty arises since without interactions their ground state is always a superfluid regardless of the band structure. Nonetheless such phases do exist at strong interactions and are known as bosonic SPTs [@Chen2011; @Chen2011a; @Schuch2011]. Unfortunately, experimental realizations of bosonic SPTs are scarce and, to the best of our knowledge, limited to one dimensional spin chains [@Buyers1986].

Recently there has been both theoretical [@Gennady2013; @Kane2014; @PhysRevLett.116.135503] and experimental [@Huber2015; @PhotonicsExp1; @PhotonicsExp2; @PhotonicsExp3; @Paulose23062015; @Chen09092014] interest in the notion of classical topological phases mimicking the phenomenology of their quantum counterparts. A typical strategy there is to consider systems 