Tialdarí Hall was a building structure located in the city of Ellesméra and was the ancestral home of Arya's family. It had many gardens near it. Arya showed it to Eragon in Eldest. In one of the gardens in Tialdarí Hall, Arya showed Eragon the flower that Fäolin created for her.
During Roran and Katrina's stay in Ellesméra, they stopped in Tialdarí Hall, which gave Roran inspiration for his castle in Palancar Valley. When Roran accompanied Eragon during his departure from Alagaësia, Katrina remained behind with their daughter in the Hall.
There was possibly an entry phrase because when Arya entered she chanted: "Root of tree, fruit of vine, let me pass by this blood of mine."