Hii...

As you ask about best architecture college in Tamilnadu so these are colleges..

• National Institute of technology
• Anna university
• Radhinam school of architecture 
• SRM engineering college
• Excel college of architecture and planning

To know more about colleges click here:

Hello, 

Below are the few best colleges in tamilnadu for architecture-

• National Institute of Technology - [NIT], Thiruchirapalli
• Anna University, Chennai - Course & Fees Details
• B.S. Abdur Rahman Crescent Institute of Science & Technology - [BSAU], Chennai
• SRM Engineering College, Kanchipuram
• Sathyabama Institute of Science and Technology, Chennai
• Excel College of Architecture and Planning, Namakkal
• Dr. M.G.R. Educational and Research Institute, Chennai

Hope this helped. 

Good luck! 

Hii..

Some of the best colleges for architecture in Tamil Nadu are 

• National Institute of Technology - [NIT], Thiruchirapalli
• Anna University, Chennai
• Rathinam School of Architecture - [RSA], Coimbatore
• B.S. Abdur Rahman Crescent Institute of Science & Technology - [BSAU], Chennai
• SRM Engineering College, Kanchipuram
• Sathyabama Institute of Science and Technology, Chennai
• Excel College of Architecture and Planning, Namakkal
• Meenakshi College of Engineering, Chennai
• Tamilnadu School of Architecture - [TNSA], Coimbatore

Hope this helps. 

Best of luck