How to spawn a prefab randomly only once

I'm working on a small game, where the player has to find their home. Ideally the house would spawn at a new location every time the game is played. I am new to coding so I'm not sure if what I have made works/ make sense. So far I added a condition to check if the house(right now just a cube) is in the game. However I have no idea if it is working. Without the condition the cube does keep spawning. I am also having trouble spawning the cube in a different location each time. It shows up in the same spot no matter what. ![alt text][1] This is what happens without the condition. [1]: /storage/temp/200147-my-pink-world-prototype-pc-mac-linux-standalone-un.png **Code below:** using System.Collections; using System.Collections.Generic; using UnityEngine; public class RandomPlacement : MonoBehaviour { public GameObject cubePrefab; void Update() { if (cubePrefab ==true) { Spawn(); } void Spawn() { Vector3 randomSpawnPosition = new Vector3(Random.Range(0, 11), 50, Random.Range(0, 11)); Instantiate(cubePrefab, randomSpawnPosition, Quaternion.identity); } } }