Authorities say it took 100 firefighters to put out the 4-alarm fire.
The building was vacant and no one was hurt.
Authorities don't know what started the fire, but firefighters are looking closely at some nearby powerlines. It appears a transformer exploded.
The hotel was built in 1904. It became a Texas landmark 60 years later. It was being transformed into apartments with shops, restaurants, a swimming pool and a speakeasy bar.
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