the bastion and the island are free and open 24/7. March 15 is a public holiday - some places are still open - it's up to each museum, baths, etc. Usually this info is missing from the websites, so you need to call the places of your choice to make sure they are open.
Anyway you can still take part in the celebrations :-)
I guess everything (except for restaurants) is going to be closed on March 15.
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