First, let me tell you that I'm not Catholic. But having lived in Europe for several years, I've probably been in more Catholic Churches than most Catholics. Not that this makes me an expert, but more of a connoisseur. However, I have asked several of my Catholic friends how to best appreiciate a Catholic church (including the Priest I worked with in Italy) and here are their tips:
Tip #1: Be mindful of the cultural practices, modesty is still a big deal in the churches in Europe. Before going into a Catholic church make sure to cover your shoulders and knees. This is out of respect for the Lord and not because the church thinks shoulders and knees are bad.
Tip #2: Pay attention to the art. Many of the pieces have stories behind them that could be inspiring even to a non-Catholic. Throughout the churches there are many depictions of the Old and New Testament, see if you can recognize them. During times of low literacy the walls of the church served as a "poor mans Bible". If some of the art makes you uncomfortable, it's ok. “The world offers you comfort, but you were not made for comfort. You were made for greatness!” -Pope Benedict XVI
Tip #3: You can light a candle. The light represents the light of Christ and the smoke going up to heaven is our prayers being lifted up and presented to God.
Tip #4: If you have been baptized in any Christian denomination you can use the holy water, it is a reminder of our baptism. When we bless ourselves we recognize and remember our death to self and resurrection in Christ.
Tip #5: When entering the church look for the side chapel (most churches have one). There you should find the tabernacle, an ornate enclosure that holds the Eucharist, the body of Christ. There is usually a red candle present to signify that He is there.
Tip #6: A non-Catholic should not go up for communion. This is out of respect for differing beliefs and because Catholics believe that partaking in the Eucharist in a state of mortal sin is not something that should be done.
Tip #7: If you are in Europe, specifically Italy, know that most places don't do the blessing thing during communion (where you walk up with your hands across your chest to receive a blessing instead of the eucharist) which is a common practice in the US for non-Catholics participating in a Catholic service. If you do this the Priests will think you want the eucharist. It's awkward for everyone so just stay in the pew; not everyone goes up during communion anyways.
There you have it, a few suggestions to get you started as you explore the Catholic churches around Europe. I hope you enjoy them, some of the churches are insanely beautiful! Also shoutout to my Catholic friends for their help with this post (especially Alanna), you guys rock!
Have other tips or suggestions? Let me know in the comments section!