City Gate refers to an entrance or exit point in a city, often marked by a significant structure or archway. Historically, city gates served as defensive barriers, controlling access and protecting inhabitants from invaders. They were typically built in strategic locations and could be adorned with sculptures or inscriptions. In modern times, many city gates have become historical landmarks or tourist attractions. They symbolize the city's heritage and culture, often representing the architectural style of the period in which they were built. Examples include the Brandenburg Gate in Berlin and the Porta Nigra in Trier.