On the American Airlines homepage, locate the flight search box.
Click on the "Advanced/Multi-city search" link, typically found below the "Round Trip" and "One Way" options.
Enter the details for each leg of your journey. For our cruise, this would look like:
Flight 1: Depart from your home airport (e.g., LAX) to Barcelona (BCN) to arrive on or before Date.
Flight 2: Depart from Rome (FCO) to your home airport (e.g., LAX) on or after Date.
Search for flights and select your desired class of service for each leg. Be sure to compare the prices to a standard round-trip booking to see the potential savings.
Please note that these types of fares are subject to availability and can change. If you encounter any difficulties, consider using a flight comparison tool.