Yes, May Day is a real holiday.
In some countries, it's Internatiol Labour Day (explains why Arya is off of work), others it's just a day of celebration.
I was in Rome for May Day last year, and the city shut down. No cabs, buses, or stores were open, but Oasis and a few other bands did have a concert in front of The Basilica of St. John in Lateran (ie, the most important church in the Catholic, if not the Christian, world).