Port Arthur never had its own town hall. From 1880 (as the Municipality of Shuniah) to 1907, it most frequently used the Masonic Hall as a meeting place. The building burned down in 1907.
City of Thunder Bay (CoTB) Archives
Between 1897 and 1914, Port Arthur used a wide variety of different buildings for its city council to meet. In 1914, they purchased the Whalen Building and that was the final home for Port Arthur's city council. It was never formally called "City Hall" but it's where the city council met and city offices were, and it's still owned by the city of Thunder Bay today (Thunder Bay Hydro and the city's economic development commission are based there). The town council met in a boardroom on the third floor.
The first Fort William City Hall, built in 1892. It also served as a fire hall, prison, and telephone exchange. It ironically burned down in March 1903.
Like many western Canadian cities, the town hall wasn't just a place of government. It was the primary meeting place for numerous groups (religious and secular), was rented out for special events, and was even a movie theatre for some time. This trend continues today with many different organizations using the city's council chambers to host special events or training courses, so that the space is almost always in use.
Fort William's second City Hall, built 1903. The tower was removed in 1945 after it started to collapse, and the remainder was demolished 1964 after a new building was built on the parking lot behind it.
Almost no work was done to improve the building during its existence, aside from the tower removal and some interior renovations in 1955, and by the mid 1960s it was in extremely poor condition; like Winnipeg's city hall (which was demolished just two years before) it was in such a state that parts of the building were unusable and those working in it didn't feel safe. It's not clear if it would be standing today had it been properly maintained; it was built with bricks that were improperly fired and didn't last very long, basically turning to dust over time as the water got into them and broke them apart. Some buildings in town still have these bricks, and there are voids where only mortar remains, as it was more weather resistant than the bricks it held together.
This is the building in the 1950s after the tower was removed:
A new city hall was built on the parking lot behind it in 1964 and would serve as Fort William's city hall for just 5 and a half years before amalgamation.
Amalgamation didn't seem likely at the time it was built so they only built it to be large enough for their smaller city government. Since it was the only purpose-built city hall in the city after amalgamation (it actually had a council chamber, not just a boardroom) it was the obvious choice for Thunder Bay's new City Hall.
In 2009, the city of Thunder Bay renovated the building inside and out, including the addition of several thousand square feet to the front of the building to create more office space and expand the lobby. The interior is actually pretty well done, considering how ugly the exterior looks.
The plaza in front is called MacGillivray Square.
City Hall houses only a few departments and the council chambers, with many of the more specialized agencies and departments that form the city government located in other office buildings.
The city's HR Department is located in the old Fort William Hydro Building:
They also have offices in the Whalen Building posted above, and numerous departments occupy space connected to the nearby Victoriaville Centre, which will likely be demolished soon. They occupy a former department store and BMO branch and many other offices are on the ground level of a parkade attached to the entire thing. More city workers actually work in that building than the city hall, so most city government work happens there instead of city hall. This is the best photo I can find for that building:
There is a second level behind the limestone and a basement that is used for work spaces, so with the former BMO connected to it this part of the civic centre alone has more floorspace than the city hall itself.