A 5-dimensional Einstein spacetime with (non)vanishing cosmological constant
is analyzed in detail. The metric is in close analogy with the 4-dimensional
massless uncharged C-metric in many aspects. The coordinate system, horizons
and causal structures, relations to standard de Sitter, anti de Sitter and
Minkowski vacua are investigated. After a boost and Kaluza-Klein reduction, we
get an exact solution of 4-dimensional Einstein-Maxwell-Liouville theory which
reduces to a solution to Einstein-Liouville theory in the limit of zero boost
velocity and to that of Einstein-Maxwell-diliton theory in the case of zero
cosmological constant.Comment: 18 pages, 3 figures. Minor modifications, version appeared in Mod.
Phys. Lett.