Application of structural optimization to transmission tower design is facilitated since major costs such as material, transportation, erection, and maintenance are directly proportional to structural mass. In this paper, structural topology and shape annealing (STSA), a structural topology optimization method that combines structural grammars with simulated annealing, is applied to reduce the structural mass of an existing tower. STSA has previously been validated only on smaller-scale benchmark tasks. The challenges of extending STSA for application to full-scale design tasks are presented. Key results include a 16.7% mass reduction of the existing primary members through combined optimization of the tower envelope, joint locations, and discrete section sizes. Also, the tower configuration was optimized to have 16 fewer joints and 80 fewer primary members. Promising results for a practical, full-scale application serve to validate the STSA method for combined structural optimization of topology, shape and discrete section size.