I've google searched but can't quite get a good feel on this. I will be carrying a daypack around Barcelona and wondered if there are lockers where you can store a pack while you explore the church? I read that they don't allow backpacks up the towers. And I've read that they have around 500 lockers to store luggage...but then on the website I can't find where it mentions that.

Anyone experienced this?

Thanks

Here's what is available on premises:

We don't have any lockers for suitcases. The only ones available are for storing small bags temporarily while visitors go up in the towers as, for safety reasons, no rucksacks are allowed. They must be claimed as soon as visitors return from the tower.

So if your backpack fits in their small bag storage (I wasn't there with anything so can't comment on size) then you have an on-premises option. However, if the backpack is larger then you have several storage outside the premises that you can use.