(Source: Storm King’s Thunder, page 98)

Major City: As segregated as it is (Humans above, Dwarves below; at least they talk to each other) Mirabar will be a good city for the party to rest up, restock supplies, upgrade equipment, and so on.

It is also home to one of the largest non-faction groups in the North: The Mirabar Miner's Union. They are the ones running the many mines there, as listed in the book above the city entry. The Union ensures their safety and well-being of the miners, and ensures that no funny business happens in the farm.

Of course, though, if they strike….

Teleportation Circle: The Circle is still hidden from the Mirabar authorities, and Zazspar Bronzefire makes sure it’s hidden. Or…

Micro-Worldbuilding Opportunities: …he might have moved it to a less controversial space, maybe a homestead or farm just outside of the city limits.