gusuku

300px|thumb|Walls of Shuri Castle often refers to castles or fortresses in the Ryukyu Islands that feature stone walls. However, the origin and essence of remain controversial. In the archaeology of the Ryukyu Islands, the Gusuku period refers to an archaeological epoch of the Okinawa Islands that follows the shell-mound period and precedes the Sanzan period, when most are thought to have been built. Many and related cultural remains on Okinawa Island have been listed by UNESCO as World Heritage Sites under the title Gusuku Sites and Related Properties of the Kingdom of Ryukyu.

==Philological analysis== The Yarazamori Gusuku Inscription (1554) contains phrases, "pile " (くすくつませ) and "pile up and ..." (くすくつみつけて); apparently, in these phrases refers to stone walls. In the Omoro Sōshi (16th–17th centuries), the term is written as "くすく," or "ぐすく" in hiragana. Occasionally, the Chinese character "城" (castle) is assigned to it. In later ryūka and kumi odori, the reading shiro is also used for the same Chinese character, in addition to also using 城内 (shiro-uchi; inside the castle). The references to in the Omoro Sōshi are mostly about castles and fortresses, but sacred places and places of worship are called as well. In some cases, simply refers to Shuri Castle. The Liuqiu-guan yiyu (琉球館訳語), a Okinawan dictionary written in Chinese, maps Chinese "皇城" (imperial palace) to the transcription "姑速姑" (gu-su-gu). Similarly, the Yiyu yinshi (音韻字海) assigns "窟宿孤" (ku-su-gu) to "皇城."