There were signs of progress toward restoring the Mt. Washington Tavern Monday morning. Fences cordoned off the restaurant's charred exterior and boards were nailed over broken-out windows.

Six weeks after the fire, the cause of the Oct. 31 blaze remains unknown. And because of the extensive damage, the cause may never be known, said Chief Kevin Cartwright, a spokesman for the Baltimore City Fire Department.

“Unfortunately, it does take some time. We would love to be able to on the spot say, ‘This person was smoking’ or ‘It was this electrical outlet,’” Cartwright said. 

The roof and the second floor of the building collapsed during the fire, making determining a cause exceptionally difficult, Cartwright said.

Whatever started the fire, which caused $2.5 million in damage, may never he determined, he said.

The owners of the tavern vowed to rebuild shortly after the fire.

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