Introduction:
Firoz Shah Tughlaq was a Sultan of the Tughlaq dynasty who ruled over the Delhi Sultanate in the 14th century. He was known for his architectural contributions and the founding of several cities. In this question, we are asked to identify the city that was not built by Firoz Shah Tughlaq.

Correct Answer: Tughlaqabad

Explanation:
Firoz Shah Tughlaq was responsible for the construction of several cities during his reign. Let's take a look at each of the given options and determine which city was not built by him.

a) Firozabad:
Firozabad, also known as Tughluqabad, was a fortified city built by Firoz Shah Tughlaq. It was constructed between 1321 and 1325 and served as the new capital of the Delhi Sultanate. Firozabad is famous for its massive fort and the ruins of several structures.

b) Fatehabad:
Fatehabad, also known as Firozabad, was another city founded by Firoz Shah Tughlaq. It was established in 1354 and served as a military outpost during his reign. The city is located in present-day Haryana, India.

c) Tughlaqabad:
Tughlaqabad was not built by Firoz Shah Tughlaq. It was actually constructed by his predecessor and founder of the Tughlaq dynasty, Ghiyasuddin Tughlaq, in 1321. Tughlaqabad was intended to be the capital of the Delhi Sultanate but was abandoned shortly after its completion.

d) Jaunpur:
Jaunpur was not built by Firoz Shah Tughlaq either. It was founded by Sultan Ibrahim of the Sharqi dynasty in 1394, long after Firoz Shah Tughlaq's reign. Jaunpur is known for its architectural marvels, including mosques, tombs, and palaces.

Conclusion:
In conclusion, out of the given cities, Tughlaqabad was not built by Firoz Shah Tughlaq. It was constructed by his predecessor, Ghiyasuddin Tughlaq. Firozabad and Fatehabad, on the other hand, were established by Firoz Shah Tughlaq, while Jaunpur was founded by Sultan Ibrahim of the Sharqi dynasty.