The blaze at the Obstruction of Justice House — also known as the OJ House — was reported about 3:30 a.m. Friday.
No official cause has been determined, but the police arson squad is investigating, fire Battalion Chief Kevin Kortas said.
"I'm sure it's some sort of arson. There was no electricity," Kortas said.
The structure near Heidelberg and Ellery streets on Detroit's east side dates back to 1995 as a piece of art.
The internationally recognized Heidelberg Project is the creation of Detroit artist Tyree Guyton, who has transformed his decaying, crime-ridden neighborhood into an interactive sculpture park. One house features polka dots of various colors and sizes. Stuffed animals adorn another.
Guyton said Friday that the fire "wasn't so bad" because no one was hurt.
"We're moving on. Business as usual," he said while cleaning the sidewalk outside the smoldering house.
A woman leading a tour of the Heidelberg Project Friday didn't learn about the fire until the tour group arrived.
"It was one of our faves," Quinn Hamilton said of the Obstruction of Justice House. "It's kind of sad to see it burn. It's sort of discouraging."
James Oliver, 64, lives behind the house and said he heard a rumbling before noticing the fire's glow.
"It seems like the flames were 100 feet up in the sky. It was full blast," he said.