This was one of Moore-McCormack's "Constellation" class cargo-liners. They were very nice ships, with staterooms for eight passengers. However, they were built in the mid 1960s, just before the "container revolution". As a result these ships were subsequently lengthened and converted into self-loading container ships for use in the South America trade, a run where most of the ports lacked shore-based container cranes.

Gorgeous lines...
Tomas