If you aren't looking to mosaic your rasters, it sounds like you just want to group them.  

Have a look at creating a Group Layer on the ESRI help page.

If that doesn't help, perhaps have a look at the Overview of the Raster Toolset on the ESRI help page.

Grouping Multiple Raster Layers
Found this in my garden today in Sydney, Australia (specifically Lane Cove). Can you tell me what it is?



