There are almost 46 colleges in Tamilnadu for B.Arch. You got a very good score in NATA so you can get the top colleges in Tamilnadu. I am suggesting you some of the good colleges in Tamilnadu;

• NIT, Thiruchirapalli with rating 8.2
  
• Anna University, Chennai with rating 7.7
  
• B.S. Abdur Rahman Institute of Science and Tech., Chennai with ranking 8.3
  
• Ranganathan Arch. College, Coimbatore with ranking 7.9
  
• Thiagarajar College of Engineering, Madurai with ranking 8.3
  
• VIT university, Vellore with ranking 8.4
  

These are the top colleges in B. Arch. in tamilnadu. You can choose by yourself from these and get a good academic there.