Embodiments that reassemble hierarchical representations in a closed-loop 1×N system are disclosed. Some embodiments comprise creating a flat netlist from a hierarchical representation of a 1×N building block, creating attributes for the flat netlist, and altering one or more elements of the flat netlist, such as by an operation of a logic design tool, a synthesis tool, a physical design tool, or a timing analysis tool. The embodiments further comprise generating a second hierarchical representation of the 1×N building block that reflects the altered element. Further embodiments comprise an apparatus having a 1×N compiler and a reassembler. The 1×N compiler may create attributes for a flat netlist of elements of a hierarchical representation of a 1×N building block. The reassembler may use the attributes to create a second hierarchical representation of the 1×N building block that reflects alteration of elements to the flat netlist.