There is a building in Gongwangfu that looks like a fountain. What's its name?

In Beijing, there are four such pavilions: Tanzhe Temple, Zhongnanhai, the Forbidden City and Gongwangfu. The Liubei Pavilion in Yuanmingyuan was destroyed in Eight-Nation Alliance, leaving only a stone pedestal engraved with a sink. Among them, Gongwangfu's is the smallest, because those are all used by the royal family. He Shen often holds banquets here to entertain his colleagues for their birthday. The flowing water enters from the south of the pavilion, passes through the curved waterway on the ground, and finally flows out from the north of the pavilion, and flows into the bat pond from the back channel. The water constantly symbolizes blessing and talent. The location of the water outlet is the theme, facing south, and the owner He Shen is sitting here. On his birthday, when the cup stops at which guest, the guest will put the prepared gift list in the cup, and finally the cup will float to He Shen, and He Shen will sit at the water outlet to receive the bride price, which is called "after a while". The waterway on the ground, from north to south, is a word "longevity". Looking from east to west, it is also the word "water" in cursive script, so this pavilion is also called "Shuishou Pavilion". Its uniqueness lies in its different fonts from different directions, namely water, longevity and pavilion. It means ingenious conception.