1 A tower or a palace. For example, tenshukaku 天守閣 is the keep or dungeon of a castle. See *tenshu 天守.
2 A 2-storied structure in a garden. Something that is more splendid and elegant than an arbor or a simple pavilion.
3 An exquisitely refined building, often associated with serving powdered green tea matcha 抹茶, and enjoying a display of art treasures, as for example, tea bowls *chawan 茶碗. Examples of such buildings include: the Golden Pavilion, Kinkaku 金閣 at Rokuonji 鹿苑寺 (originally built 1397, burned by arsonist in 1950 and rebuilt in 1955) ; the Silver Pavilion, Ginkaku 銀閣 at Jishōji 慈照寺 (1489) ; and the multistoried *Hiunkaku 飛雲閣 at Nishihonganji 西本願寺 (early 17c), all in Kyoto.
Jishōji Ginkaku 慈照寺銀閣 (Kyoto)
Rokuonji Kinkaku 鹿苑寺金閣 (Kyoto)