Large View Here. The Porta Nigra (Latin for black gate) is a large Roman city gate in Trier, Germany. It is today the largest Roman city gate north of the Alps and has been designated a World Heritage Site. The name Porta Nigra originated in the Middle Ages due to the darkened color of its stone; the original Roman name has not been preserved. Locals commonly refer to the Porta Nigra simply as Porta. La Porta Nigra (del latín Puerta Negra) es una puerta consolidada de tiempo romano. Es parte del Patrimonio de la Humanidad de la UNESCO. Es el monumento emblemático de la ciudad de Tréveris que es una de las más antiguas de Alemania. Los habitantes la llaman en general simplemente por la abreviatura Porta. http://en.wikipedia.org/wiki/Porta_Nigra