Twelve Shiva

 Twelve Shiva temples are connected with Mahamaham festival which happens once in 12 years in Kumbakonam. They are 

1. Kasi Viswanathar Temple, 
2. Kumbeswarar Temple, 
3. Someswarar Temple, 
4. Nageswara Temple, 
5. Ekambareswarar Temple, 
6. Gowthameswarar Temple, 
7. Abimukeswarar Temple, 
8. Kambatta Visvanathar Temple, 
9. Banapuriswarar Temple, 
10. Kalahasteeswarar Temple, 
11. Koteeswarar Temple, and 
12. Amirthakalasanathar Temple.

rituals

 https://www.google.com/search?q=Kumbakonam+ritual

https://www.google.com/search?q=Kumbakonam+rituals

Theerthams

1. Indra Theertham - provides moksham 
2. Agni Theertham - rids Brahmahatthi dosham 
3. Yama Theertham - rids fear of death 
4. Nruthi Theertham - rids from fear of evil spirits 
5. Varuna Theertham - provides long life 
6. Vaayu Theertham - rids diseases 
7. Gubera Theertham - provides prosperity 
8. Isaana Theertham - moksham (to reach Lord Siva's feet) 
9. Brahma Theertham - pacifies ancestors 
10. Gangai Theertham - provides Kailasa padavi 
11. Yamuna Theertham - provides wealth 
12. Godavari Theertham - fulfills wishes 13. Narmada Theertham - provides physical strength 
14. Saraswathi Theertham - provides Gnaanam (enlightenment) 
15. Cauveri Theertham - provides knowledge 
16. Kumari Theertham - blessings to pets 
17. Payodini Theertham - provides joy 
18. Sarayu Theertham - removes mental strain 
19. Arubathaaru(66)kodi Theertham - removes grief & provides hapiness 
20. Deva Theertham / Naaga Theertham - rids of all sins & provides Devendra's post / rids of Kaala Sarpa dosham

https://www.google.com/search?q=Kumbakonam+Theertham

Gopuram

1. Brammatheertheshwarar; 

2. Mukundeshwarar; 

3. Dhaneshwarar; 

4. Virushabeshwarar; 

5. Baaneshwarar; 

6. Koneshwarar; 

7. Bhakthikeshwarar; 

8. Bhairaveshwarar; 

9. Agasthyeshwarar; 

10. Vyaneshwarar; 

11. Umaibakeshwarar; 

12. Nairutheeshwarar; 

13. Brammeshwarar; 

14. Gangatheshwarar; 

15. Mukthatheertheshwarar; 

16. Shethrabaleshwarar

https://www.google.com/search?q=Kumbakonam+Gopuram