There are seven Sapthasthana (Saptha meaning seven) temples for Shiva in Mylapore worshipped by the Saptha rishis – Adri, Brigu, Kutsa, Vashishta, Gautama, Kasyapa and Angirasa.Originally they were all part of a single temple but in due course they have become separate temples. It is highly powerful to worship all the seven deities in a single day .
http://coffeeetime.blogspot.com/2009/11/saptha-sthaana-shiva-worship-at-seven.html

More details on the Sapthasthana temples here

1. Sri Karaneeswarar Temple

located : Bazaar street in the middle stretch of the popular Kutcheri road .Worshipped by Sage Vasishta, this 12th century .The Shivalingam here is in square shape as seen in only Thirukkadaiyur and Kalahasthi. Since Shiva is thereason for everything, He is called Karaneeswarar (Karanam in Tamil means reason).
http://indiancolumbus.blogspot.com/2009/08/mylai-karaneeswarar-temple-chennai.html

2. Sri Theerthapaleeswarar Temple

located : Dr.Natesan street of Krishnapet, Triplicane Mirsahib market area opposite to mosque , opp road Chennai City center , Lloyds road. 
Worshipped by Sage Adri, this temple is located in The temple has significance that when the seven deities of the Sapthasthana temples take bath in the sea during the Theerthavari festival in the tamil month of Masi, this deity takes the first place. Sage Agasthiar worshipped Shiva here.
http://indiancolumbus.blogspot.com/2009/08/theerthapaleeswarar-temple-triplicane.html

3. Sri Velleeswarar Temple

located : South Mada street (chitrakulam) very close to the Kapaleeswarar temple. Worshipped by Sage Angeerasa, at The legend has it that Asura Guru Sukracharyar worshipped Shiva here in order to regain his vision.
http://coffeeetime.blogspot.com/2009/11/sri-velleeswarar-temple-3rd-of-7-saptha.html

4. Sri Virupaksheeswarar Temple
located : near Karaneeswara temple in Bazaar road in the middle and Mundakkanni Amman temple. Worshipped by Sage Kutsa, this is the oldest temple of Mylapore and Sivanesan Chettiar , who built this temple, had a daughter called Poompavai and when she died, Thirugnana Sambandhar brought her back from her burnt bones. Viroopam means Contradicting the Nature and since Shiva’s third eye contradicts the nature, He is called Virupaksheeswarar.

http://coffeeetime.blogspot.com/2009/11/sri-virupaksheeswarar-temple-4th-of-7.html

5.Sri Valiswarar Temple

located : Gopathy Narayana Chetty Street opposite to Kolavizhiamman Temple & opposite Sri Karaneeswarar Temple. Worshipped by Sage Gautama, this 2000 years old temple . Vali got all his powers after his tapas towards Easwaran here. Pancha lingams came out from the earth as seen in a separate shrine which is an appropriate place for meditation. There are shrines for Vinayahar, Natarajar, Goddess Sivahami, Murugar with Valli and Deivanai, Chandeeswar, Anjaneyar, Vishnu, Durgai, and Ayyappan. Navagrahas with their respective vahanas and Saneeswarar separately are present in different shrines. In the Southwest of the outer praharam, a lizard has been carved out to indicate that this is a Parihara sthalam.

http://coffeeetime.blogspot.com/2009/11/sri-valeeswarar-temple-5th-of-7-saptha.html

6. Sri Malleeswarar Temple

located : South Mada street ,It is located in the area behind Sri Karaneeswarar Temple. Worshipped by Sage Brigu,. This was once a forest of Jasmines and so the Easwaran here is called Malleeswarar. Prarthan, King of Ayodhya, was in tapas and conducted a Yagna here towards Shiva. Indhran tried to sabotage his tapas but could not. In praise of the intensity of his tapas, Shiva appeared before him along with his consort. Neem and Aswatha trees are grown together as a single tree.
http://coffeeetime.blogspot.com/2009/11/sri-malleeswarar-temple-6th-of-7-saptha.html

7. Kapaleeswarar Temple

Worshipped by Sage Kasyapar, this is the most popular of the Sapthasthana temples. This is one of the 275 Thevara Padal Petra Sthalams; out of these, this is one of the 40 temples that have west facing Shiva shrines. The original temple was located near the sea but got submerged in the sea and the current temple was built around 350 years back. Parvathi Devi worshipped Shiva here in the form of Peacock. The 63 Nayanmar festival is highly popular .