The Mishna on today’s daf discusses building projects that should not be done in partnership with non-Jews. Such projects include building a basilica, a gardom (a tribunal), an itztadeyya (a stadium), and a bima (a platform). Nevertheless, one may join them in building pedestals and bathhouses, although when they reach the arched chamber in which an idol is placed, the Jew must not build.
The Rambam and Ra’avad explain the prohibitions as based on the general concern with Avoda Zara. All of the buildings that are forbidden included stages and altars built for idol worship, which would make it impossible for Jews to play a role in their erection. Other rishonim view the prohibition differently. The Ritva writes that these were places of judgment, and since the pagan legal system killed people without proper reason, Jews should not assist them in building such courts. Rashi argues that there is even concern that Jewish people will be killed so that helping to build these buildings may play a role in the murder of Jews. According to the Meiri, different parts of legal proceedings took place in each of these buildings. He adds that the Talmudic rule dina d’malkhuta dina – that “the law of the land is the law” – notwithstanding, that applies to monetary judgments and not to capital crimes.
According to Rashi, the pedestals that can be built in partnership with non-Jews were not directly built for idol worship, as they could be used to hold any object. Most of the other rishonim have other readings for this word, including a different type of bathhouse (Tosafot, Ramah), palaces (Rambam) or other building used for leisure activities or entertainment (Re’ah, Ritva). Such public buildings often included arched chambers in which idols were placed which made the niche for the idol considered to be a place of actual avoda zara.