This paper reports the first experimental observation of unidirectional backscattering-immune topological electromagnetic states (CESs) in a magneto-optic photonic crystal (PhC). The study demonstrates that these CESs can travel in only one direction and are immune to backscattering from obstacles, a property analogous to the quantum Hall effect (QHE) in electronic systems. The research uses a square lattice of magnetized ferrite rods to localize a unidirectional waveguide mode at the edge of the structure adjacent to a metallic wall. The unique properties of these CESs arise from nontrivial topological properties of the bulk band structure, which are characterized by Chern numbers. The study shows that the CESs are robust against disorder and can navigate around obstacles without scattering, a feature that could enable new classes of electromagnetic devices and experiments. The experimental system is based on a gyromagnetic PhC with a metallic cladding, and the results are supported by numerical simulations and theoretical predictions. The study highlights the potential of photonic systems for realizing topological quantum numbers and their applications in areas such as optical isolators and slow light. The research also demonstrates the feasibility of using photonic crystals for studying topological phenomena, offering a new platform for exploring topological physics in classical and bosonic systems. The results have significant implications for the development of robust, high-performance photonic devices and systems.This paper reports the first experimental observation of unidirectional backscattering-immune topological electromagnetic states (CESs) in a magneto-optic photonic crystal (PhC). The study demonstrates that these CESs can travel in only one direction and are immune to backscattering from obstacles, a property analogous to the quantum Hall effect (QHE) in electronic systems. The research uses a square lattice of magnetized ferrite rods to localize a unidirectional waveguide mode at the edge of the structure adjacent to a metallic wall. The unique properties of these CESs arise from nontrivial topological properties of the bulk band structure, which are characterized by Chern numbers. The study shows that the CESs are robust against disorder and can navigate around obstacles without scattering, a feature that could enable new classes of electromagnetic devices and experiments. The experimental system is based on a gyromagnetic PhC with a metallic cladding, and the results are supported by numerical simulations and theoretical predictions. The study highlights the potential of photonic systems for realizing topological quantum numbers and their applications in areas such as optical isolators and slow light. The research also demonstrates the feasibility of using photonic crystals for studying topological phenomena, offering a new platform for exploring topological physics in classical and bosonic systems. The results have significant implications for the development of robust, high-performance photonic devices and systems.