Bath No. 5 is one of the public sulphur bathhouses in Abanotubani, the old bath district that helped give Tbilisi its name. Follow the neon sign and you will find a straightforward, local-feeling bath rather than a polished spa.
The men's section has showers, a hot pool, and a sauna; the women's public section is simpler. Bring slippers and a towel or rent them there, and budget a little extra if you want the scrub and massage.