Banquet Pine Grove - En no Matsubara

...That is, because of these factors, the floor plan was thought to be of the so-called Hokuketsu type, with its northern edge bordering the Hokkyoku-oji road in the Kyoto area, but recent research has shown that the original palace (first Heian Palace) was of the so-called Fujiwara-kyo type, with two blocks of space between its northern edge and Hokkyoku-oji road, and that at the end of the 9th century, it was extended two blocks northward to form the Hokuketsu type (second Heian Palace), in order to develop the Okura warehouse complex, and at that time two more palace gates were added, one on the east side and one on the west side, bringing the total to 14 gates. As for the Imperial Palace, there was a certain space to the west of it called "En no Matsubara," which was unique to the Heian Palace. It could have been a plaza for banquets or space for when the Imperial Palace was rebuilt, but there is no evidence of either, so it is unclear.

*Some of the terminology that refers to "Banquet Pine Grove" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…すなわちこれらによって平面構成は，その北辺が京域の北極大路に接する，いわゆる北闕（ほつけつ）型と考えられてきたが，近時の研究により，当初の宮城(第1次平安宮)は，その北辺と北極大路との間に2丁の空間をもつ，いわゆる藤原京型であったこと，それが9世紀の末，大蔵倉庫群の整備のため北へ2丁拡大延長されて北闕型(第2次平安宮)となり，その際宮城門も上東，上西の2門が設けられ14門となったこと，などが指摘されている。　内裏については，平安宮独自のものとして，その西方に〈宴（えん）の松原〉と呼ばれる一定の空間があった。饗宴のための広場とも，内裏を建て替えるときのための余地とも考えられるが，ともにその事実がなく，明らかでない。…

※「宴の松原」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報