Look for the "Map Seed" or "Map Number" text box (usually at the bottom right of the settings menu). Type in your 5-digit code.
: The starting island is ideal for heavy production, while a "Farmer Island" to the south provides Potatoes and Grapes to keep your main population happy. Seeds for Anno 1404: History Edition
If your goal is to maximize population, land area is your biggest bottleneck. These seeds are known for spawning some of the largest buildable landmasses in the game: Anno 1404 Wiki
: Best for those who want a "huge" map with oversized islands.
: Specifically noted for being highly convenient for the Venice expansion's unique mechanics.
While the top three are the safest, these "portable" seeds are excellent for specific challenges: