Real-time systems, and in particular safety-critical systems, are a rich source of challenges for the program verification community as software errors can have catastrophic consequences. Unfortunately, it is nearly impossible to find representative safety-critical programs in the public domain. This has been significant impediment to research in the field, as it is very difficult to validate new ideas or techniques experimentally. This papers presents open challenges for verification of real-time systems in the context of the Real-time Specification for Java. But, our main contribution is a family of programs, called CDx, which we present as an open source benchmark for the verification community. Categories and Subject Descriptors D.2.4 [Software Engineering]: Software/Program Verification; C.3 [Special-Purpose and Application-Based Systems]: Real-time and embedded systems General Terms Verification, Experimentation