Concept:
Nalanda University was one of the world's oldest and most renowned centres of higher learning. It flourished during the Gupta period and attracted students and scholars from many countries such as China, Korea, Tibet and Sri Lanka.
• Founded during the Gupta period (5th century CE).
• Patronized by rulers such as Kumaragupta I and Harshavardhana.
• Famous Chinese scholar Xuanzang (Hiuen Tsang) studied here.
Step 1: Identify the location of Nalanda University.
The ancient Nalanda University is situated in:
\[
\boxed{\text{Nalanda district, Bihar}}
\]
The modern Nalanda University has also been established near the ancient site in Bihar.
Step 2: Understand its historical importance.
Nalanda was known for:
• Buddhist studies.
• Philosophy.
• Mathematics.
• Astronomy.
• Medicine and Literature.
Thousands of students from different parts of Asia came here to study.
Step 3: Compare the options.
• Haryana -- Incorrect.
• Karnataka -- Incorrect.
• Tamil Nadu -- Incorrect.
• Bihar -- Correct.
Step 4: Final conclusion.
Hence, Nalanda University is located in:
\[
\boxed{\text{Bihar}}
\]