Buildings are constructed by humans and intended to last for a very long time. If you think about a force that may destroy buildings around you, you may think about explosives or devastating weapons.
When you walk through a decaying piece of industrial brownfield, you get to know a different type of destructive force: mother nature.
When a building is constructed, nature loses some area wich is now occupied by human beings. When those buildings are abandoned and left-behind, nature slowly takes back the area step by step.
First you can see a few colonies of moss on the masonry or on the roof tiles. Ferns follow and after a few years, other plants like grass of even trees are growing all over.
While grass, plants and moss break down the masonry very tardily, the roots of a tree (i.e. birches) can disintegrate a wall within a few years.
Once I saw a building with a few trees on the rooftop. When I entered the building on the ground floor, I saw that the roots of the birches thrilled down from the roof to the joints of the masonry in the ground story.
So as time passes by, those mosses, ferns, plants, trees and other vegetation are able to dismantle huge buildings and raze them to the ground.
By the way, sometimes people help nature destroying those buildings like in this bakery:
A police squad did an exercise with explosives in this building. Fortunately we weren’t in there when they did that ;-)