Big objects like containers, cars and trucks covering sections or parts of the fence may prove to be a significant security problem and should be avoided. The fence should have several other gates that can be opened and used in case of the main gate becomes inaccessible. If you have a wall made of concrete or bricks you probably doesn't need to reinforce the wall. Except if the wall is the only thing between a public place and something's very important or valuable. Otherwise they will offer the same protection as hollow-core wooden doors.
Concrete blocks placed in front of wooden walls prevent forced entry by vehicles.
Walls should be stripped on objects that could serve as ladders for intruders trying to reach the roof or windows. A window is a likely entrance point for intruders. If possible the glass should be of high-strength type. However windows is also many peoples first choice in case of fire, this should be taken in to the consideration during planing. Fire safety considerations preclude the use of certain window coverings.