I saw an old World of Interiors article about Japanese bathhouse design and immediately clicked through. I wish it had even more pictures, but I did learn a new fact:
Though bathhouse styles vary from region to region, sentō can nevertheless be divided into two broad categories: Tokyo and Osaka style. The former are almost without exception extravagant places, always arranged with a washing area in front and baths behind. The relative uniformity of sentō design around the capital is a consequence of the catastrophic Great Kantō earthquake of 1923. In the aftermath, it was shrine carpenters who turned their talents to restoring the sentō: their architectural approach, complete with meditative murals of Mount Fuji and similar motifs, became the established regional style.