The divyadesam Thiruththanka (thiruththaNkA) is in Kanchipuram. It is also known as Vilakkoli Perumal Sannidhi. It has been praised by Thirumangai Azhvar in his Periya Thirumozhi 10-1-2

ponnai mAmaNiyai aNi ArndhadhOr
minnai vEngadaththu uchchiyil kaNdu pOy
ennai ALudai Isanai empirAn
thannai yAm senRu kANdum thaNkAvilE

and in his Thirunedunthandagam 14

muLaik kadhiraik kuRungudiyuL mugilai mUvA
	mUvulagum kadandhu appAl mudhalAy ninRa
aLappariya Aramudhai arngam mEya
	andhaNanai andhaNar tham sindhaiyAnai
viLakkoLiyai maradhagaththaith thiruththaNkAvil
	veqAvil thirumAlaip pAdak kEttu
valarththadhanAl payan peRREn varuga enRu
	madakkiLiyaik kaikUppi vaNanginALE

pasurams.

It was near this divyadesam that Vedanta Desikan was born. The Perumal here is called Vilakkoli in Tamil and Deepa Prakasha in Sanskrit. Swami Desikan wrote a stotra in praise of this Lord - he also included the great meanings of Sharanagati in this work. As such this work came to be called Sharanagati Deepika. Who can perform Sharanagati, what is the nature of Sharanagati, the greatness of those who have performed Sharanagati and such matters have been explained in a simple manner by Swami in this work. This work is equivalent to granthas such as Nyasa Dasakam, Nyasa Tilakam and Nyasa Vimshati.