Palma Cathedral in Mallorca is one of the more recognizable churches I've visited recently. It's a Romanesque church with a heavy, simple exterior (you can tell from the colors), but the interior features artistic dome frescoes and some more modern-style murals. Very Renaissance.
Although the price felt a bit high, and we only had a quick look without delving into its history and cultural significance, we still spent about an hour exploring it.
A must-see for everyone visiting Palma.