Ýdalir
Ýdalir is mentioned only in stanza 5 of the poem Grímnismál, found in the Poetic Edda. In this stanza, Odin (disguised as Grímnir) informs young Agnar that Ullr has a home in Ýdalir. Here's a translation of the stanza (Ýdalir is translated as Ydalir):