Monolithic applications, characterized by their unified structure where all components are tightly integrated and deployed together, remain a prevalent architectural choice in enterprise environments, legacy systems, and high-performance applications. These applications present unique challenges for continuous integration and continuous deployment (CI/CD) processes, including slow feedback cycles, long build and test times, complex dependency management, risky database migrations, and high deployment risks. To address these challenges, best practices such as automating and optimizing testing, using caching and parallel execution in builds, implementing careful database migration strategies, and employing feature flags and progressive delivery are recommended. CircleCI is highlighted as an effective CI/CD platform for monolithic applications due to its enterprise-grade performance, scalability, efficient resource utilization, and integration capabilities with monitoring and database migration tools, thereby enabling teams to optimize software delivery and manage large codebases effectively.