Board Thread:Suggestions forum/@comment-27703999-20160321174730

Everyone knows the Dwarven Doors, at day they look like normal stone, but at night, the door becomes visible. Maybe it is an idea to do the same thing, but then with Gates. So you can only see those gates at night. You can use this to make bigger gates then only Dwarven Doors for - for example - the gate of Moria.

Maybe it's an idea that you can open this gates only at night. In the Hobbit the Dwarven Door of the Lonely Mountain can only be opened with a key when "The last light of Durin's day will shine upon a keyhole." 