An interactive look at what certain areas of New York City, past and present, look like uses a moveable, diving slider to shift between the two images on NYC Grid (a website seeking to map all of NYC, street by street).
Tesseract is a term that describes the "wrinkling" of time and space, allowing two points to be connected through this fifth dimension rather than forcing you to travel on a straight line. For example, if you take points A and B and connect them with a piece of string, the shortest route would be to walk along the straight piece of string. But in tessering, you could wrinkle the string, or fold it upon itself, so that points A and B would be right next to each other, allowing you to just walk across. It is how the people travel to distant planets in A Wrinkle in Time.