Character goes through walls

Hi,

I've created a character and a simple map. I want to trigger the character to go from point A to point B. I have managed to do that using Vector3.MoveTowards but the character goes through walls on its way to point B. Does anyone have any idea how should I stop that, or has any other suggestion how can I program the character to go from its origin position to target?

 ![using UnityEngine;
 using System.Collections;
 public class move : MonoBehaviour
 {
     public float speed = 1.0f;
 
     private Transform target;
 
     void Awake()
     {
         //character origin.
         transform.position = new Vector3(-4f, 0f, -3f);
 
         //create cylinder as target.
         GameObject cylinder = GameObject.CreatePrimitive(PrimitiveType.Cylinder);
         Camera.main.transform.position = new Vector3(0.85f, 1.0f, -3.0f);
 
         // set target coordinates and make the object invisible.
         target = cylinder.transform;
         target.transform.localScale = new Vector3(0f, 0f, 0f);
         target.transform.position = new Vector3(2.18f, 0f, 2.67f);
 
        // Position the camera.
         Camera.main.transform.position = new Vector3(1.85f, 5.0f, -7.0f);
         Camera.main.transform.localEulerAngles = new Vector3(15.0f, -20.0f, -0.5f);
 
     }
 
     void Update()
     {
         // Move our position a step closer to the target.
         float step =  speed * Time.deltaTime; // calculate distance to move
         transform.position = Vector3.MoveTowards(transform.position, target.position, step);
 
         // stop when reach the target.
         if (Vector3.Distance(transform.position, target.position) < 0.001f) return;
         
     }
 }][1]

[1]: /storage/temp/171085-unity.png