In this work, the ferroelectric domain structure of (Pb0.79La0.21)TiO3 transparent ceramics and its response to an applied electric field were investigated by piezoresponse force microscopy (PFM). A qualitative three-dimensional reconstruction of the domains by PFM measurements revealed that the domain structure consists in stripes in two size scales (micro and nanometer) separated by 90A degrees domain walls coexisting with 180A degrees domains. While the nanoscale 90A degrees domains were found arranged in organized structures, (e.g., lamellas, herringbones, and other unusual configurations), the 180A degrees domains form a "labyrinth" structure, typical of ferroelectrics with a degree of disorder. Local application of an electric field reveals different coercive voltages to reorient 180A degrees and the two types of 90A degrees domains and the appearance of a different nanoscale 90A degrees domain structure after poling. While the labyrinth structure is destroyed with relative low voltages, the created 90A degrees domains structure persists, avoiding the formation of a single-domain structure.