Check Out vectorpoem’s Ultima 4 Map Viewer
To better enable some nostalgic reflection about Ultima 4 and the way in which it fostered a very imagination-driven sort of game playing (one can relate; I’ve had this same experience playing Ultima 6), vectorpoem decided to write a little utility to load in the world map and shape data from the MS-DOS version of the game, and display it (fully animated, mind you) in a small window on the desktop.
You can grab a copy of the utility from vectorpoem’s website, or from the brand new project entry created for it here at the Codex. Also included, at either site, is a download of the SHAPES.EGA and WORLD.MAP files from Ultima 4.