A building where the abbot of a monastery (or other senior officer temporarily assuming the place of abbot) takes a high seat (kōza 高座) to preach the dharma (seppō 説法) to an assembly of monks and lay followers, and may engage members of the assembly in debate (mondō 問答). Such gatherings in a dharma hall are referred to as "convocations" (jōdō 上堂).
In medieval Japanese Zen monasteries built on the Song Chinese model, the dharma hall was a massive structure that stood on the central north-south axis of the campus, to the north of the buddha hall (butsuden 佛殿) and the mountain gate (sanmon 山門). It was of post-and-beam construction with a gabled tile roof and stone floor, and it housed a large Sumeru altar (shumidan 須彌壇) that the abbot would mount for convocations. The architectural features and internal arrangements of dharma halls were identical to those of buddha halls, with the exception that the altar had no image on it. When the abbot took the high seat on the altar he sat facing south, in place of the buddha. The arrangement also mirrored that of the audience hall in the imperial court, where the emperor sat on a dais facing south, his courtiers lined up in rows on the east and west sides.
In Japanese Zen today, only a handful of Chinese-style dharma halls survive, mostly at a few Rinzai school head monasteries in Kyoto and Kamakura. The two Soto head monasteries, Eiheiji and Sōjiji, both have buildings called dharma halls, but in their architecture and internal arrangement those facilities are actually just very large main halls (hondō 本堂). In fact, no Soto monasteries or temples today have traditional Chinese-style dharma halls with stone floors and altars devoid of images. They all have main halls, which combine the functions once held separately by buddha halls and dharma halls. Although Standard Observances of the Soto Zen School refers to a dharma hall in various contexts, it is understood that the observances in question will take place in a main hall. →"main hall," "convocation."