I was overseas last month with my Verizon iPhone 5 and the pre-paid 4G SIM card that I purchased only gave me 3G service on my phone. I'm wondering if the Verizon 5S has "worldwide" 4G LTE?
Here is a list of LTE networks in Europe. Spain's Orange seems to be running LTE on band 3 and 7. If you have a iPhone model A1533 it should support LTE on band 3 at least.
My guess is, that there was no 4G coverage at your location. You can check the coverage with this map.
Martin81, thank you for your help and the info you've provided. It doesn't make sense to me, then, that my iPhone 5 from Verizon only got 3G service in the city center of Madrid. LTE was even enabled in the phone's settings.
I'll probably be upgrading to a 5S soon. Hopefully Apple got the necessary antennas crammed into the S model.