A brief ancient history on inefficiency of the Trump "WALL"

Strategies
Artillery machines were used to pound walls and towers with huge boulders with the aim being to breach or collapse a section of the defense to allow foot soldiers to attack the besieged army inside. The most widely used devices operated using a single swinging arm, which is why they are often called beam-sling machines. Boulders were the most common ammunition, but alternatives included flaming missiles covered in pitch or containers made from wood, terracotta or glass containing a flammable liquid...

Types of Catapults
The different types of Catapults used in the Middle Ages included:

The Ballista - The Ballista was similar to a Giant Crossbow and worked by using tension
The Trebuchet - The massive Trebuchet consisted of a lever and a sling and was capable of hurling stones of various weights, with a range, which often exceeded 300 yards.
The Mangonel - Missiles were launched from a bowl-shaped bucket.
http://www.lordsandladies.org/catapults.htm

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Artillery machines were strategically positioned to target a specific area on extremely thick fortress walls; and their operators worked in shifts so that a target could be continuously bombarded.

Aside from physical damage, the sight of a battery of artillery machines being assembled in full view must have been a daunting one for those under siege. There were also other strategies besides the brute force of launching heavy objects at the enemy.