This new architectural class of macromolecules has received substantial attention during the past decade. Three dendritic subclasses, which include (a) random hyperbranched (i.e., one-pot ABx, polymerizations), (b) dendritic grafted (i.e., Combburst® polymers) and (c) regular dendrons/dendrimers (e.g., Starburst® dendrimers) have been synthesized and characterized at a well-defined level in our laboratory. It is clear that their precisely controlled, nanoscale dimensions and architecture play critical roles in influencing physical properties and performance characteristics. Furthermore, these parameters have also distinguished dendrimers as fundamental modules for many nanotechnology applications, as well as for the construction of a new class of larger nanoscale entities which we have termed core-shell tecto(dendrimers). This account will overview these activities and focus on certain unique de Gennes dense packing (or congestion phenomena) and nanoscale container properties that have emerged from this novel architecture.