Explications:

Dear [Name],

I hope this postcard finds you well. I'm currently on holiday in the beautiful city of Barcelona. Yesterday, I visited the famous Sagrada Familia and was blown away by its grandeur and beauty. The architecture was simply stunning and I felt so small in comparison.

Today, I walked around the Gothic Quarter and was struck by its charm and history. The narrow streets and old buildings made me feel like I was transported back in time. I also tried some delicious tapas at a restaurant and was pleasantly surprised by how flavorful they were.

Overall, I'm having an amazing time exploring this vibrant city. I wish you were here to share these experiences with me. See you soon!

Best regards,

[Your name]