CyberSecDome is a cyber defense platform that combines digital twin technology, AI-powered security tools, and virtual reality interfaces to protect digital infrastructures. The platform consists of four core components: Digital Infrastructure, Virtual Infrastructure with digital twins, AI-Empowered Security Tools, and a VR-based Interactive Collaborative User Interface. The Virtual Infrastructure creates a Digital Twin-based Cyberrange that enables safe training and testing environments, bridging offline research with real-time system performance monitoring. Users can interact with systems without affecting production environments. The AI-Empowered Security Tools include Intrusion Detection and Prediction (IDP) that analyzes network data for abnormal behaviors, Incident Investigation capabilities, Dynamic Risk Analysis, Automated Penetration Testing, and Dynamic and Adaptive Intrusion Response (DAIR) for automated incident handling. These tools analyze data from both digital and virtual infrastructures to provide incident forensics and situational awareness. The VR-Interface provides real-time 3D visualizations of cybersecurity status, combining human and AI capabilities for enhanced response. The interface offers dynamic visualizations that support evaluation of defense strategies. Multiple CyberSecDome instances can be interconnected to form a "Global CyberSecDome" network. This network includes Threat Information Sharing tools for exchanging threat intelligence and AI-Knowledge Sharing tools that enable sharing of AI models while maintaining privacy of training data. The platform maintains operations during cyber-attacks through continuous monitoring and automated response capabilities.