A superb map of Madrid in the times of the late Spanish Habsburgs.
You can download it as a georeferenced (EPSG:25830) ECW file and also get the Spherical Mercator TMS-style tiles from here. With these, you will be able to do some nice tile replacements – not only with gvSIG Mobile for Linux, but also with any other software that uses the z/x/y scheme to store tiles:
First available level: z = 10; x = 501; y = 386
Last available level: z = 18; x = 128376; y = 98847