P&O first introduced passenger services in 1844, with a leisure cruise departing from Southampton to the Mediterranean. These voyages were the first of their kind and the forerunner of modern cruise holidays. The company later introduced round trips to destinations such as Alexandria and Constantinople and underwent rapid expansion in the later half of the 19th century, with its ships becoming larger and more luxurious. One particularly notable ship of the era was the SS "Ravenna", built in 1880, which became the first ship to be built with a total steel superstructure.