I'm currently visiting India, and I went to the town of Cuddalore in Tamil Nadu. It contains a place called Thiruvahindram, one of the 108 Divya Desams. As I discuss in this question, the Alwars (also spelled Azhwars) are a group of 12 ancient Vaishnava saints who lived in Tamil Nadu and are famous for their poetry in praise of Vishnu. The Alwars are crucially important figures in the development of Vaishnavism; it is the principles and beliefs embodied in the Alwars' poems that ultimately gave rise to the Sri Vaishnava sect (of which I'm a member). The Alwars praised many Vishnu temples and other sacred places of Vishnu in their poetry; a sacred place of Vishnu that was praised by at least one Alwar is called a Divya Desam, and there are 108 of them; see the list here.
In any case, there are many special things about Thiruvahindrapuram. The main Vishnu deity is called Devanatha Perumal:
Once the gods needed help to defeat some Asuras, so they prayed to Vishnu in Thiruvahindrapuram. Vishnu appeared and killed the Asuras with his Sudarshana Chakra (discus weapon). Afterwards he wanted water, so his bird vehicle Garuda started digging for water with his beak, creating a body of water known as Garuda Theertham. But he was taking too long, so Vishnu's serpent Adiseshan used his tail to quickly dig a well for Vishnu. Another thing about this place is that right next to the Devanatha Perumal temple is a hill, formed from a part of Mount Oushadi which fell while Hanuman was carrying it. (I discuss that story in my answer here.) And on top of that hill is a temple to Vishnu's incarnation Hayagriva, who appeared before the Sri Vaishnava Acharya Vedanta Desikan.
I could ask so many questions about this sacred place, but for now let me just ask one. The priest of the Devantaha Perumal Vishnu temple said that the sage Markandeya and Bhumidevi engaged in Tapasya (deep meditation) here, and Vishnu appeared before them. When I heard this, at first I just assumed that this was about Vishnu's wife Bhumidevi, goddess of the earth; Vishnu married her after she engaged in Tapasya. But then I went to the famous Upillaiappan Vishnu Temple near Kumbakonam. That is where Vishnu, in his Venkateshwara form, married the sage Markandeya's daughter. Markandeya's daughter was an incarnation of Lakshmi and her name was Bhumadevi.
So my question is, who is it that Vishnu appeared before in Thiruvahindrapuram? Did he appear before Bhumidevi goddesss of the Earth, or before Bhumadevi daughter of Markandeya? The latter seems more plausible to me, since it would make sense that Markandeya and his daughter would together engage in Tapasya in order to get Vishnu as a groom.