The button to open the leaderboard is at the bottom of the chatbox pane, tournament and alliance box, and troops and supplies box of the main window, basically the bottom center of the screen. Brown with white lettering.
The default view shows you the top ten players on your domain. Originally it was set up as a paged set, so you can page to 11-20, 21-30 and so on. Since then, the developers have changed it in which you can only go one page at a time. At the bottom of the page, you can search for players by name, or search for alliances altogether.
When you view the top ten list or search for a player, you get a listing on player names by might. Each player has a "view" button on the far right that you can click to view more. More info, in this case, includes the names and coordinates of each of their cities.
When you search by alliance, you get a similar list of players. This feature comes in handy when in war with another alliance.
Apparently the solution to hacking was to just start giving the city information out to everyone.
- Players under the effect of Potion of Mist will not be found by this tool. Their city coordinates are protected in this list.
- During war time, when alliances have each other marked as hostile towards another then those Alliance cannot search each other for coords in the Leaderboard.