Explanation: Agra Fort, located in Agra, Uttar Pradesh, is a historical monument that is often referred to as a 'Walled City.' This term is used to describe a fortified urban area that is enclosed by walls and often includes a complex of buildings within its boundaries. Agra Fort is a prime example of such a structure, built by the Mughal Emperor Akbar in the 16th century.
The fort is surrounded by a massive wall that is approximately 2.5 kilometers in length and 20 meters in height. This wall is made of red sandstone and is punctuated by four gates, each with its own unique architectural features. The fort's walls not only served as a defensive structure but also as a symbol of the Mughal Empire's power and grandeur.
Within the walls of Agra Fort, there is a complex of buildings that includes palaces, mosques, audience halls, and other structures. These buildings were constructed by various Mughal emperors over a period of several centuries, each adding their own architectural style and features. The fort's architecture is a blend of Indian, Persian, and Islamic styles, reflecting the diverse cultural influences of the Mughal Empire.
The fort's urban planning is also noteworthy. It was designed to serve as a royal residence and administrative center, with different areas designated for various functions. The fort's layout includes residential quarters, administrative buildings, and religious structures, all of which are interconnected and designed to function as a cohesive urban unit.
Agra Fort is not only a historical monument but also a UNESCO World Heritage site, recognized for its architectural and historical significance. It is a prime example of a 'Walled City' and is an important part of Uttar Pradesh's rich cultural heritage.
In contrast, the Taj Mahal, while also a significant historical monument in Agra, is a single structure and not a walled city. Similarly, Bada Imambada in Lucknow is a significant religious structure but does not fit the description of a walled city. Therefore, Agra Fort is the correct answer to the question of which monument is described as a 'Walled City.'