Monitoring multi-agent systems at scale presents significant challenges, as traditional approaches fail to address the complex interactions and vast data these systems generate. Key issues include observability gaps, emergent behavior detection, communication bottlenecks, resource contention, security vulnerabilities, consistency in state management, latency and timing problems, and scalability of monitoring infrastructure. Each challenge involves unique technical difficulties, such as the "observability trilemma," where completeness, timeliness, and low overhead are difficult to achieve simultaneously, or the detection of emergent behaviors which standard metrics often miss. Solutions like distributed tracing, pattern recognition, decentralized communication frameworks, and specialized monitoring platforms like Galileo are proposed to overcome these challenges. Galileo, in particular, offers features tailored to multi-agent environments, providing comprehensive visibility and effective solutions to ensure system resilience and performance as these systems expand.