These were huge structures scattered across the surface of Rigel IV, and one of the main features of that trade-oriented world. Visiting merchants and starship officers, who had passed the tedious inspection by Rigel Space Control and were permitted to land, could visit a Trade Hall to aid in their business. There were more traditions and rituals here as well, but with a more relaxed and business-like atmosphere.
In the fast-paced and rapidly fluctuating economy of Rigel IV, the staff of a Trade Hall provided their experience, knowledge and expertise to visiting merchants and helped arranged trades, for reasonable fees. Staff would post a merchant's cargo on the planet's information network and search for a cargo they could take back. These searches involved a range of different values, currencies and product names in different languages, and required great skill. Although the Trade Halls charged according to effort, they only charged on successful searches, so they only gave up when the search threatened to cost more than the commodity. Through the Trade Halls, goods could be traded directly for others of high value at very low prices. More experienced merchants could choose to use their own contacts, however, and paid so much less in fees.
There were some cargos that even the Orion-run Trade Halls would refuse to handle for reasons or illegality or risk, though these could be exchanged in other, disreputable places on Rigel IV.
Each Trade Hall was owned or controlled by an old and respected Orion family or group of smaller families. Many of them kept estates on Rigel III (FASA RPG module: The Orions: Book of Common Knowledge).
The Trade Halls were in operation for thousands of years, possibly since the Rigellians opened up the Rigel system to all races for trade and development circa 988,000 BCE (reference stardate −9900/00). The Rigellians later became a signatory to the Treaty of Kammzdast, which governed the use of Orion slaves, though they never traded in them. From November, 1508 BCE (stardate −35/0811), the Rigellians used their subtle influence to allow Orions to work as clerks in their Trade Halls, giving the slaves more influence of their own (FASA RPG module: The Orions: Book of Deep Knowledge).
Many spacefaring Orions applied, and within a few decades there were Orions working in every Hall. By 1317 BCE (stardate −33/17), they formed the majority of the clerical workforce. Orion clerks were valuable, efficient and obedient workers in the Trade Halls, and in close touch with Rigel's economics. The master races were displeased with the growing Orion independence, but it let it continue because of the increased riches it brought them.
In 14th July 95 BCE (stardate −20/9507.14), a Trade Hall was the site of the 187th Rigel Conference, where the Nine Worlds Confederation issued the Ultimatum of the Nine Worlds, a list of prohibitions restricting Orions from participating in any commercial activities in or out of the Rigel system (likely including the Trade Halls). The Orions panicked and triggered a revolt. Which of them did what was unknown, and it was theorized that a captain of the guard ordered the meeting chambers sealed, or an overzealous Trade Hall family scion attempted a coup, or a technician cut the communications.
This lead to the appearance of the great Orion leader Nallin the Unconquerable, who led a group of Trade Hall rhadamanen ('arch-executives') in an uprising of the Orion slaves against the Kammzdast signatories. They consolidated their control over every Trade Hall before journeying to the Orion homeworld of Rigel VIII, liberating the planet and beginning the Orion War for their independence (FASA RPG module: The Orions: Book of Common Knowledge).