Emergency services were called to The Old Piano School, in Appleton Gate, Newark, at around 7.30pm on Wednesday (18 May) evening.
No casualties were reported but significant damage was caused to the building.
The cause of the blaze is still under investigation, but officers are appealing for witnesses who may have seen anything suspicious.
Detective Inspector Nicholas Hall, of Nottinghamshire Police, said: “This was a large fire that led to the evacuation of several neighbouring properties.
“We are currently working with our colleagues at Nottinghamshire Fire and Rescue Service to understand how this blaze started.
“We would therefore like to hear from anyone who was either in the area at the time, or who has additional information on what happened.”
Anyone with additional information is asked to call 101 quoting incident 703 of 18 May 2022.
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