Unity doesn't support parsing an array from json. This JsonHelper will help.

Building.cs

using System;
using UnityEngine;

[Serializable]
public class Building
{
	public string ID;
	public string Name;
	public double Area;
	public float Height;
	public byte Floor;
	public int Room;
	public float Longitude;
	public float Latitude;
	public string Detail;
}

jsonFileExample.json

{ "Items" : [
  {
    "ID":"Cube1",
    "Name":"A cube",
    "Height":"100",
    "Floor":"0",
    "Room":"0",
    "Longitude":"123",
    "Latitude":"321",
    "Detail":""
  },
   {
    "ID":"bridge1",
    "Name":"Bridge",
    "Height":"4",
    "Floor":"0",
    "Room":"0",
    "Longitude":"33",
    "Latitude":"2",
    "Detail":""
  }
  ]
}

JsonHelper.cs

using System;
using UnityEngine;

public static class JsonHelper
{
	public static T[] FromJson<T>(string json)
	{
		Wrapper<T> wrapper = JsonUtility.FromJson<Wrapper<T>>(json);
		return wrapper.Items;
	}

	public static string ToJson<T>(T[] array)
	{
		Wrapper<T> wrapper = new Wrapper<T>();
		wrapper.Items = array;
		return JsonUtility.ToJson(wrapper);
	}

	public static string ToJson<T>(T[] array, bool prettyPrint)
	{
		Wrapper<T> wrapper = new Wrapper<T>();
		wrapper.Items = array;
		return JsonUtility.ToJson(wrapper, prettyPrint);
	}

	[Serializable]
	private class Wrapper<T>
	{
		public T[] Items;
	}
}