If you aim to be the cultural epicenter of the world, this is the victory for you. The first civilization to possess a total number of Visiting Tourists that exceeds the Domestic Tourists of each other civilization in the game wins the Culture Victory.
Tourism is generated by Trade Routes, shared (or conflicting) late game Governments, open borders, Great Works housed in your civilization, Relics housed in your civilization, Holy Sites, National Parks, Artifacts, and wonders.
TEAM CULTURE VICTORY
To win a Team Culture Victory, an individual team member's Visiting Tourists must exceed the Domestic Tourists of all non-team member civilizations. Visiting Tourists are not shared between team members.