God Shiva is omnipresent so He resides in each and every element in this universe, there is no such place where Shiva doesn't exist.
When you have Shiva in your thoughts, your mind, then you see Shiva in the Panchabhootas( five elements of the nature) and in every living being. When you see a Shiva linga, you can see the Mahadev in it, else it would be a mere stone to you, when you don't believe and love God Shiva.
Coming to the question what are the must visit temples as a Shiva Bhakt, I feel every Shiva temple which has a Linga is a must visit.
But if you want to grow spiritually and realise that this materialistic things are all perishable and the only one who is Nityamu(forever) and Satyamu (truth) is Shiva, then the must visit temple is Kashi Vishwanath Temple.
The Kashi temple visit for me was a life changer. I can't describe in words, the wonderful spiritual experience I felt in the holy and favourite place of Shiva.
- Foremost, seeing the beautiful Ganga River I was spellbound, since I don't consider Ganga as just a water body, but as a mother who provides life and helps you to wash away few sins. When I touched the water, I could feel a mother cuddling a baby, could see her beautifully flowing and take a permanent place in God Shiva’s hair. Ganga stretches to a massive 2500 kms, I thought Oh Shiva, Ganga which is in Kashi is just a part of the huge River, how could you hold such massive River in your hair ?? My Mahadev, I bow to you.
- The Ganga Aarti which is performed daily in the evening is a must watch to feel the spiritual bliss.
- The various temples like Kalabhairava, Annapurna, Vishalakshmi, the Shakti Peetas, Vyasa Lingam ( the linga which was installed by Sage Vyasa) etc. around the main Kashi Vishwanath temple are amazing.
- The boat ride in the holy Ganga which covers all the 64 Ghats is beautiful ( Ghat means the steps which lead us to the river Ganga).
- The most important thing which will lead us to vairagya and self questioning is when we see the dead bodies which people bring from across the country to perform last rites here in the Harishchandra Ghat. Seeing the continuous burning of the bodies ( at once six pyres are lit), make us realize that the beautiful physical body which we always boast of, will turn into a pile of ash one day.
- And according to Shiva Purana, Mahadev daily at afternoon 12 comes to take a dip in the holy Ganga at the Manikarnika Ghat, smearing the cremation ash on His body.
- You can find many sanyasis in Kashi wearing the Saffron clothes, vibhoothi smeared on their entire body, Rudraksha mala around their necks, holding a trishul, having matted hair and chanting the mantra “ Namah Shivaya “. Mahadev is present in every atom of this holy city Kashi, which is believed to be created by Himself as the city rests on Mahadev's trishul.
I conclude by saying that, Kashi is a holy place, which is to be visited at least once in your lifetime. If I have another birth, then I would pray Shiva I be born in Kashi , the moksha provider place.
Om namah Shivaya
Om Kashi_Vishwanathaya Namaha
Om Kashi Annapurneshwari Namaha
Om Kashi Vishalakshi Namaha