Sagrada Familia (home)
Tying in with this year's La Mercè celebrations, the Sagrada Família is opening its doors to the public for three days for free; but hurry - you have to apply for tickets and the first day is already fully booked up.
From September 22nd to 24th, from 4 to 8pm, you will be able to get in to Antoni Gaudí's work-in-progress cathedral for free, providing you have booked tickets in advance through Ticketmaster. You will be given a specified time slot that you will be to visit the Barcelona landmark, which also includes a projection of how it will look in 2026, the year that the basilica is due to be completed.
Note that the museum and towers will be closed, and the audio guide service will not be available. You will also have to provide a credit card when booking, but no charge will be made; the card details are necessary to be able to pick up your invites from a La Caixa ATM.
Find full details here at the Ticketmaster website (in English).