Five days is a comfortable minimum for several neighborhoods, food and a day trip.

Five days is a comfortable minimum for several neighborhoods, food and a day trip.
Three to four days covers the tall towers and the downtown area, the older district around the creek, a beach afternoon and a desert experience.
Three to four days covers the Gothic Quarter, the main Gaudí buildings, a beach afternoon and an evening or two of late dinners.
Four to five days lets you see the major landmarks, a couple of museums and a few neighborhoods without rushing.
Four to five days lets you see the major museums and monuments without rushing, plus a slower day in a neighborhood like the Marais or Montmartre.
Four to five days lets you see the major museums and monuments without rushing, plus a slower day in a neighborhood like the Marais or Montmartre.
Three to four days covers the historic center, the Vatican and a couple of neighborhoods at an unhurried pace.
Four to five days covers the main museums, a West End show and a couple of neighborhoods.