4th Wall is a free, augmented reality (AR) public art platform developed by Nancy Baker Cahill Studio Inc. It aims to explore inclusive creative expression through the use of AR technology. The app offers two main features: "Coordinates" and "AR Artworks".

With the "Coordinates" feature, users are able to experience curated, collaborative, site-specific, public AR art exhibitions. By physically being present at specific locations, users can view AR artworks created by artists that activate historically, politically, or culturally significant sites. This feature aims to inspire dialogue and expand our understanding of public art.

The "AR Artworks" feature allows users to view, explore, and place Nancy Baker Cahill's dimensional drawings in their preferred environment. Users have the ability to rotate, scale, place, and even record their interactions with the drawings.

The latest update of the app provides a more streamlined user experience by removing unnecessary buttons and expanding the curated and site-specific "Coordinates" platform. Additionally, artworks may now include sound, indicated by a new orange sound button at the top of the menu. The "Refresh" button updates the nearest artwork based on the user's location, and the "About" button directs users to the 4th Wall website. The app is compatible with iPhone 6s running iOS 11 or above.

Overall, 4th Wall offers a unique and immersive experience for art enthusiasts to engage with AR artworks and explore the intersection of art and technology.