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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Gareth Bennett AM has caused outrage amongst his peers and the transgender community after commenting about the rights of minority groups.
Some brighter spells in between, especially later in the day but feeling cold despite higher temperatures than recent days.
The Met Office has issued a yellow 'be aware' weather warning of ice for parts of Wales overnight and into tomorrow morning.