When you arrive at CosmoCaixa, you will be in Floor 0. Go down to Floor -1 and find the registration area next to the Tau Room. See the images below, taken from Cosmocaixa website.
2. Show the QR code to one of the volunteers, who will give you an ticket to the Cosmocaixa.
3. Go the the registration desk to collect your badge and lanyard. Write down your name and affiliation on both sides of the badge.
4. Proceed to the entrance of the Cosmocaixa Museum through the turnstiles, by scanning the Museum ticket. Keep the ticket, as it will allow you to go in an out during the day.
5. Go down the escalators to the auditorium, located in Floor -2. Sala Àgora is also accessible from Floor -2, but also from Floor -3, through the terrace where food will be served.
6. If the auditorium is full, you will need to wait in a line for somebody to leave.