Landmarks are regions which give extra bonuses. They change their location every two weeks. You can locate the landmarks by tapping the Landmark button at the top of the screen [Front view].
Monte Cassino gives a bonus of 30% Unit Hitpoints
The Peenemünde gives a bonus of 50% Production Speed
Stalingrad gives a bonus of 30% March Size
Wojtek the Bear gives a bonus of 100% Gathering Speed
FAQ: The 50% Landmark Bonuses don’t work.
Please note that the 50% bonus applies to your Base numbers. The time you typically see when producing units has already some bonuses applied (Commander bonuses, VIP bonuses, Skill bonuses), so it is shorter than it should normally be (if you were only producing units at the given value of your base). Thus, the time cannot be reduced by half, but a percentage of the one you previously had. You can see your overall bonuses in the Buffs menu (tap on Power).