re: Buying tour tickets overseas - declined

You could just also buy the tickets the day you land, as long as you're not booking a tour same/next day. That's what 8 of us did during lunch the day before after landing in BCN, and it was high season.

I don't know for sure, but the fraud system for Sagrada Familia is seeing a foreign bank, a foreign phone number, and is reading your GPS location, and presuming (among other factors) that you're attempting to execute a fraudulent transaction. It's most likely your banks, though. Ask to be routed to the anti-fraud department, instead of talking to a regular rep.

My bank removed the ability to add travel alerts to cards, which made my life worse. I had to spend 25 minutes on the phone with Chase? to tell them, yes, I was really trying to check into a hotel in BCN while sitting in the lobby. But in England, it didn't happen.