Mid and West Wales Fire and Rescue Service says 11 of its crews are continuing to fight the fire at the National Library of Wales.
It is advising people "to stay away for safety."
This video - from viewer Edward Mulgrew - shows firefighters pumping water onto the library roof earlier.
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A 60-year-old woman died after being trapped naked in an airing cupboard at a holiday complex near Machynlleth.
Patchy drizzle will continue tonight, with coastal low cloud soon moving back inland.
Barclays has announced 203 job losses at its Merchant Services Operations and Technology Divisions in Pentwyn.