To book a multi-city trip on Lufthansa, passengers can start by selecting the "Multi-city" option on the airline's website. From there, they can enter their departure city and travel dates, as well as the cities they want to visit and the dates they want to travel between them. Lufthansa multi city offers a multi-city booking option for passengers who want to visit multiple destinations on a single trip. With this option, passengers can book flights to several cities and return to their original departure city, all on one itinerary.