How can I easily find structures in Minecraft?

I would like to find and explore some Minecraft structures, like Temples, Dungeons and more. My current way if finding these is to go straight and look around while walking. This isn't very efficient, as I find only few to none buildings each trip.

How can I effectively find generated structures? I don't mind using commands.

Minecraft 1.11 and 1.12 feature a new command: /locate:

This command returns the closest structure of the type you entered. The syntax is:

/locate <structureType>

Here is some more information about the command, taken from the Minecraft Wiki

• Accepts: EndCity, Fortress, Mansion, Mineshaft, Monument, Stronghold, Temple and Village.

  • Desert temples, Jungle temples, Witch huts and Igloos all go under the Temple category.

• Pushes coordinates for the closest structure of given type in the chat for the player who executed the command.

• Returns the message "Located [Structure] at [x] [y] [z]".

• Will display the Y coordinates as "(y?)" for some structures

If you have the seed that was used to generate your world, you can use mineatlas.com to get a map of your world, and optionally show locations where villages, temples, ocean monuments and similar are generated.

If it's a local game, you can just upload your level.dat file (it's in the saved game directory), no need to look up the seed yourself.

If it's a game on a server, you might be able to get the seed using /seed, however, most server owners disable that command to prevent players from cheating. With a local game, /seed works as well, even without cheat mode, so you can use this as well if you don't want to upload the level.dat file or can't find it.

@CAD97 commented that there's another tool Amidst that does the same thing locally so you don't need an internet connection.