Trierer Dom (left) and Liebfrauenkirche, Trier, Rhineland-Palatinate, Germany.
The Cathedral of Saint Peter (German: Trierer Dom) is a church in Trier. It is the oldest cathedral in the country. The edifice is notable for its extremely long life span under multiple different eras each contributing some elements to its design, including the center of the main chapel being made of Roman brick laid under the direction of Saint Helen, resulting in a cathedral added on to gradually rather than rebuilt in different eras. Its dimensions, 112.5 by 41 m, make it the largest church structure in Trier.
The Liebfrauenkirche (German for Church of Our Lady) is one of the most important early Gothic cathedrals in Germany and falls into the architectural tradition of the French Gothic cathedrals.(http://en.wikipedia.org/)
Since 1986 both Churches are on the UNESCO list of World Heritage Sites.

Featured in Unique Buildings of the World on January 25, 2011, featured in International Point Of Interest and Frame In Frame