The main gate to Shirotori Garden

Take a look at the entrance gate to Shirotori garden.
An interesting point to notice is the curve of the roof just above the entrance.
It is traditional Japanese carpentry work called 「唐破風」(karahafu).

Since elegant shapes were very much favored by feudal lords, it added more value to the building when this style was used.

There is another factor why it was often used at the entrance of traditional buildings such as castles, temples, shrines and palaces.

On rainy days, a curved line lets falling rain run to both ends of the curve, which prevents guests from getting wet from water running of the roof edge above the entrance.
So, the designer of the garden used this style for the benefit of visitors on rainy days.