Mud—the fine-grained silts and clays together with organic materials—stands alongside water itself as the most basic of materials in coastal and riparian zones across much of the world. In varying concentrations and contexts it forms the wetlands and mudflats, the beaches and dunes, the islands and riverbanks that cities like Manaus, Mumbai, Baltimore, and Buenos Aires rely on and fight against. There are modern monuments all around the Baltimore Harbor. For the last 50 years a system of landforms called dredged material containment facilities (DMCFs) have been created to house the mud dredged from the harbor. But the DMCFs are also cultural landscapes whose simple geometric forms are evidence of ingenuity, the evolution of environmental protection, the necessity of maritime shipping, the physical fact of mud in a port town, and the cultural desire to make it go away.