Trinayaneswara Temple has many peculiarities. First of all , this temple is older than the palace, even older than the Wodeyar dynasty itself.
Second , this is the oldest Shiva Temple in Mysore.Its origin is believed to be in 9th century AD.
In this temple the principal deity is Shiva as Vedamurthy. That is Shiva as the lord of the four Vedas (Rigveda,Yajurveda,Samaveda and Atharvaveda ).
According to legents sage Trinabindu did penance in this spot (then on the shore of a lake). Impressed by this lord Shiva appeared before the sage. Trinabindu consecrated a linga here. Since the installation of the linga is associciated with Trinabindu, it was called Trineswara. And also as Trinayaneswara (the one with three eyes) as lord Shiva is considered to have a third eye on his forehead.
As mentioned earlier, the original temple waas on the banks of the then Devaraya Sagara ( Doddakere). Later during the regimes of Kanthirava Narasaraja Wodeyar and Dodda Devaraja Wodeyar the fort got expanded and the Trinayaneshwara temple came inside the permises of the now enlarged fort. Also the Doddekere tank got drained due to the health conserns of the royal family.
Thanks to the royal patronage, an otherwise humble temple of Trinayaneswara was renovated with additional structures around it. It appears that there was even a large Chola style tower, similar to the Sri Bhuvaneswhari Temple and Shweta Varahaswamy Temple of the palace. The tower was destroyed in 18th century. However you can still see the stone built base of the tower that makes the entrance to the temple compound.
It is practice among kings to install there own images in their favorite temple in the form of worshiping the deity. In Trinayaneswara temple too you can spot the images of the images of the kind in a praying attitude with folded hands( Anjalimudra).
Apart from this there are numerous images of the gods and other mythical themes.
Close to the inner wall, along a pavilion there is along row of lingas and Nandis (bull) facing each lingas.
Also there are images of Dakshinamurthy ( an an aspect of Shiva as a guru (teacher) of universal knowledge), Kshetrapala ( the lord of the land), Kumara ( the lord of war), Surya (sun as god).
One of the highlight of this shrine is the 11kg (24lb) ceremonial gold mask of the principle idol. The mask is called Swarna Kolaga or Chinnada Kolaga is kept in the state treasury. During the day of Shivaratri (Night of Shiva) the ornament is brought to the temple. Shivaratri ( according to the Hindu Calender ) is celebrated during the mid February every year. The gold mask was gifted to the temple by the erstwhile maharaja of Mysore Jayachamaraja Wodeyar in 1951.
Trinayaneswara Temple appears as part of the stately gateway (Jaymartanda Gateway ) facing the palace in the east.