What a jyotirlinga is

A jyotirlinga is a linga of Shiva that is worshipped as a column of light rather than as an installed idol. There are twelve of them, in twelve towns, and a shrine in any one of the twelve is treated as a single place with its own name and its own legend.

Where the twelve come from

The Shiva Purana and the Nandi Upapurana carry the passage the Somnath Trust quotes on its own history page, in which Shiva says he is present everywhere but especially in twelve forms and places. That is the sentence every one of these pages leans on: the twelve are a set because the text makes them a set, not because they sit on one road.

The order, as the temples themselves print it

The traditional verse names the twelve in sequence, a sequence that runs across the country. The Bhimashankar Trust prints it on its own site, in the transliteration below. This is the order the temples use when they describe themselves, and it is why Somnath is called the first and Grishneshwar the twelfth. It is the order the hymn names them in, not a travel route.

Saurashtra Somnath cha, Srishaile Mallikarjunam, Ujjayinyam Mahakalam, Omkaram Mamaleshwaram. Parliyam Vaidyanatham cha, Dakinyam Bhimashankaram, Setubandhe tu Ramesham, Nagesham Darukavane. Varanasyam tu Vishvesham, Trayambakam Gautamitate, Himalaye tu Kedaram, Ghushmesham cha Shivalaye.

The twelve, in the order the hymn names them in

Each line above is drawn from that temple's own page sources. Where a source has not been read yet, the line says so instead of describing the temple from general knowledge.

How they group, and why that decides a trip

The twelve are spread over eight states and about 2,900 km, so no single trip is a clean line through all of them, and no official travel order exists. What actually makes a trip work is the railhead: the station that gets a traveller closest to each temple. The groups below are built on those stations, which are checked per temple and printed on each temple's page.

What the twelve do not share

They are not one kind of place. Some are hill temples with a walk at the end, some are city temples inside a corridor, one is an island, one sits on a coast road, and one is open only part of the year. Darshan is a couple of minutes at some and an hour of corridors and theerthams at another. Each temple's page states which of these it is, from that temple's own source.

Somnath (1)The first of the twelve, on the Arabian Sea at Prabhas Patan near Veraval in Gir Somnath district.Mallikarjuna (2)In the Nallamalla hills at Srisailam.Mahakaleshwar (3)In Ujjain on the Shipra, and the one jyotirlinga where Shiva is worshipped as Mahakal, the king of time.Omkareshwar (4)On the Narmada in Madhya Pradesh, 77 km from Indore and 13 km from Mortakka, where the river splits around Mandhata island, about 4 km long and 2 km wide, also called Shivpuri..Kedarnath (5)In the Garhwal Himalaya, in the region the official site calls Kedar Khand, and held by it as one of the Char Dham and of the Panch Kedar.Bhimashankar (6)In the Sahyadri hills of Maharashtra, at the headwaters of the Bhima, in Nagara style, with a core the trust dates to the 13th century and a sabhamandap added in the 18th..Kashi Vishwanath (7)In Varanasi on the Ganga, the Vishweshwara jyotirlinga and the temple that holds the city's devotional focus..Trimbakeshwar (8)At Trimbakeshwar in Nashik district, in the Sahyadri, at the source of the Godavari..Baidyanath (9)At Deoghar in Jharkhand, Baidyanath Dham, also called Kamana Linga, the linga of wishes.Nageshwar (10)On the coast between Dwarka and Bet Dwarka in Devbhumi Dwarka district, a swayambhu jyotirlinga in an underground sanctum, with a 25 m statue of a seated Shiva and a garden with a pond.Rameshwaram (11)On Rameswaram island in Ramanathapuram district, reached over the Pamban bridge.Grishneshwar (12)At Verul, near Chhatrapati Sambhajinagar, built in red volcanic rock in the Hemadpanti style and the twelfth of the twelve.