The fire broke out at the Union Theological College on Rugby Road at around 7.40am.
It is understood the building where the fire started is part of current restoration and extension work.
Twenty-seven college residents were moved out of the building and there are no reports of any injuries.
The building the fire started is in is known as the Principal's House.
It has been left badly damaged.
Clouds of dark smoke could be seen from across the city as three fire appliances rushed to the scene.
It is not yet known how the fire started.
The college underwent a major renovation in 2003 at a cost in excess of £2m and work on a further extension began in 2008.
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