Panchayatana

Sri Omkareshwara is also called Panchayataneshwara as this Linga represents the Samashti or totality of the

1. Panchayatana - 
1. Aditya, 
2. Ambika, 
3. Ganesha, 
4. Vishnu and 
5. Sadashiva. 
2. Worshipping this Linga grants one the merit of a lifetime of Panchayatana Puja.

Five Lingas

Though there are innumerable Shiva Lingas in Kashi, five are considered most sacred:

1. Vishwanatha 
2. Omkareshwara 
3. Krttivaseshwara
4. Kapardishwara and 
5. Madhyameshwara  

1. Sri Omkareshwara is also called Panchayataneshwara as this Linga represents the Samashti or totality of the Panchayatana - Aditya, Ambika, Ganesha, Vishnu and Sadashiva. Worshipping this Linga grants one the merit of a lifetime of Panchayatana Puja.
2. Lord destroyed Gajasura, wore his skin as cloth and came to be known as Krttivaseshwara in Varanasi. One who worships Krttivaseshwara attains Kaivalya even while living in a physical body. One attains Ashta Siddhis by worshipping this Linga and ascends to Kailasa. The secret place in Kashi which houses this sacred Linga is known only to advanced Yogis.
3. Kapardishwara Linga is also called Papanasheshwara as mere remembrance of this Linga destroys one's sins. By taking bath in Pishacha Mochana Kunda and worshipping Kapardishwara, even the greatest of sins like Brahma Hatya Dosha are destroyed. Kapardishwara is considered as important as Sri Vishwanatha in Kashi.
4. Originally, the city of Kashi has been described as Panchakroshapura and the Linga situated in the centre of the city is called Madhyameshwara. Lord Shiva is ever present in this Linga along with Sridevi and Rudra Ganas. Krishna is said to have worshipped Lord Shiva at this place. Taking a bath in Mandakini and worshipping Sri Madhyeshwara grants one the merit of one hundred Maha Yagnas.
5. Traditionally, the city of Kashi is said to begin with Madhyameshwara and end with the shrine of Dehali Vinayaka.  

Silence

The merit of keeping total silence for one's complete lifetime is obtained by observing Mauna Vrata for a fortnight in Kashi. Lifetimes would be insufficient to describe the greatness of the holy city of Kashi.

Antargriha Yatra is yet another significant Yatra prescribed by scriptures like Kashi Rahasya and Kashi Darpana. On the decided day, one should keep the vow of silence, worship Pancha Vinayakas and perform the Samkalpa for Antargriha Yatra. The Yatra should begin with a bath in Manikarnika and worship of Manikarnikeshwara and Siddhi Vinayaka. The Devetas to be worshipped during this Yatra are:

Sankata Ghat - Vasukishwara, Parvateshwara

Lalita Ghat - Sri Lalita Devi and Ganga Keshava

Mir Ghat - Jarasandheshwara

Manmandir Ghat - Adi Varaheshwara, Somanatha, Dalabhyeshwara

Balmukund Chauraha - Brahmeshwara

Agastya Kund - Agastyeshwara

Jangamvadi - Kashyapeshwara, Harikeshaveshwara

Kodayi Chauki - Vaidyanatheshwara, Dhruveshwara, Gokarneshwara

Hatakeshwara - this is considered to be a very secretive spot not revealed to all.

Hastikshepa Tataka - this was lost during floods in Ganga.

Raj Darwaza - Kikaneshwara

Govindpur - Bharabhuteshwara, Chitragupteshwara

Chanduki Gali - Chitraghanta Devi

Pashupatishwara

Pitamaheshwara - Shitla Gali

Brahmapur - Kalasheshwara

Siddheshwari mandir - Chandreshwara

Vira Tirtha - Vireshwara

Nimvali Brahmapuri - Vidyeshwara

Agnishwar Ghat - Agnishwara

Bhonsle Ghat - Nageshwara

Sankata Ghat - Harishchandreshwara, Chintamani Vinayaka, Sena Vinayaka, Vasistheshwara, Vamadeveshwara, Sima Vinayaka

Lahari Tola - Karuneshwara, Trisandhyeshwara, Sri Vishalakshi

Dharma Kupa - Dharmeshwara

Vishwabhuja Devi

Mir Ghat - Asha Vinayaka, Vrddhaditya

Sakarkandaki Gali - Chaturvaktreshwara, Brahmishwara

ManaHprakameshwara

Sakshi Vinayaka

Kotwalpur - Ishaneshwara

Kalika Gali - Chandika Devi, Chandishwara, Bhavani Shankara, Shukra Kupa

Sri Annapurna

Sri Dhundhiraja Gajanana

Rajarajeshwara

Khova Bazar - Langulishwara

Nakulishwara

Paranneshwara - Jnana Vapi

Dandapani, Paradravyeshwara, Pratigraheshwara, Nishkalankeshwara, Markandeyeshwara, Apsareshwara, Gangeshwara, Nandikeshwara

Tarakeshwara

Mahakaleshwara

Moksheshwara and Virabhadreshwara

Avimukteshwara - Sri Vishwanatha 

Chakra

To obtain Sudarshana Chakra from the Lord, Narayana performed penance in Kashi. He created a Pushkarini and filled it with water that emanated from his body. On the banks of this Pushkarini, Narayana performed a severe penance for eighty thousand years. Pleased with his penance, the Lord appeared with Bhavani and blessed him with Sudarshana Chakra. Hence, this Pushkarini came to be known as Chakra Pushkarini.

http://bullinformation.blogspot.com/2013/03/lord-shiv-and-lord-rishabh-study-more.html

Immensely pleased with Narayana's devotion, Lord shook his head in bliss and his earring fell into the Pushkarini. As the Lord's Karamani (the earring) fell into it, the Tirtha also came to be known as Manikarnika.  

Sins

Those who commit sins knowingly in this sacred city will attain Rudra Pishacha Yoni and will be punished by Bhairavas till they are absolved of their sins.

Rama

Lord Mahadeva utters Rama mantra in the ear of a dying person in Kashi and grants him Moksha.

Brand

http://www.brandbharat.com/english/up/districts/Varanasi/Varanasi.html