​The logical synthesis of extended solids has been a long-standing objective in chemistry. The fundamental problem is that attempts to link molecular building units into extended structures often led to amorphous or poorly crystalline solids. Our research has turned this "dream" into reality by making metal-organic frameworks. We showed that metal-oxide clusters could be used as anchors for joining organic linkers into robust crystalline open frameworks. This approach was then generalized by using other clusters, from the almost forgotten arsenal of poly-nuclear acetates of metals, and vast number of organic linkers to build an extensive class of porous frameworks. We found that the clusters' rigidity impart directionality and thus it was crucial in building structures by design. This was elaborated to make for the first time materials with controlled porosity, pore-functionality and metrics. We also showed that organic molecules can be linked by covalent bonds to make covalent organic frameworks and molecularly woven frameworks. This "reticular chemistry" has led to the design of structures with exceptional porous properties making them useful in many applications such as the storage of hydrogen and methane, selective capture of carbon dioxide and its conversion to fuels, and harvesting water from desert air.