National Museum Wales union members in strike over pay
Staff at six National Museum Wales (NMW) sites have walked out in the first of a series of strikes planned throughout the summer holidays.
Public and Commercial Services (PCS) union members walked out at 13:00 BST in a row over pay and pensions cuts.
Members of staff working on weddings were not expected to join the strike.
A NMW spokesman said it was "very disappointed" with the strike and apologised to affected customers.
Geraint Parfitt, vice-chairman the PCS union at St Fagans, explained why they were taking the action.