Hidden Test Maps

The Hidden Test Maps is a set of two small maps that are featured in Grand Theft Auto IV.

Description
As the name suggests, these two maps were created for testing purposes and are normally hidden in the game, thus cannot be reached without using Modifications. These maps are technically added along with Liberty City and the State of Alderney, but were placed way above the height limits.

These test maps are internally named as well, called "CJ Test" and "Animviewer":

CJ Test
Named after CJ Dick, Rockstar Lead Prop Artist, this map contains several objects used in the game, starting from small, breakable objects such mailboxes, shopping carts and wooden fences to larger, unbreakable objects such wooden lightposts, trees and a FlyUS passenger plane. The ground contains large portions of different textures, both soft and hard surfaces, and small building interiors used for clothing shops (Perseus, Modo and Russian Shop), laundromats and the normally-inaccessible shop featured in Bull in a China Shop. Also, there is a stack of explosive barrels.

This map also contains the two hidden rooms used for the Venturas Poker Challenge and The Men's Room, two TV shows, as well as another room that has no collision detection, which can only be seen with the correct modification (one that can move Niko to anywhere and without falling).

Animviewer
This map is depicted as a flat terrain with staircases, platforms, unique concrete walls and some objects. As the name suggests, it is intended for animation testing, like running, crouching, taking cover and ragdoll animations when the character falls from a considerable height. At night, several colourful lights can be seen.

Trivia

 * It is possible to spot NPCs on the test maps.