This video was one of the sessions during our Event-Driven Microservices Conference 2020. Project Klokwrk aims to become a showcase and blueprint of a complex system based on clean architecture principles. We have noticed that the internet is flooded with fragmented and oversimplified Hello World examples that become useless for starting complex implementations. Drawing from our experience of modernizing a 50-year-old legacy system, we wanted to consolidate the lessons we have learned and turn them into an open-source project. Following CQRS and event sourcing principles, Project Klokwrk leverages Axon Framework to demonstrate an opinionated way to structure an application in a clean architecture manner. In this workshop, we will dive deep into technical details of two interesting Klokwrk features: how it helps in defining software architecture, and how it solves integration and component testing (with event replay).