MapAbility.com has a nice set of information about VMAP0 and VMAP1, data sets created by the National Geospatial-Intelligence Agency (a branch of the US Government) to provide a basic world-level dataset.

The data sets are large and quite detailed, with VMAP0 being at 1:1,000,000 and VMAP1 being at 1:250,000. Although the NGA has a data portal with navigation, the site at MapAbility.com provides points for direct access to the data files, which is a bit nicer if you want to collect the whole set.