Seoul's Sadong-san   서울사동산
the Four Guardian Hills of inner-NE Seoul
part of the Bukhan-san Sub-range
Nak-san, Anam-san,  Gohwang-san  &  Baebong-san
낙산      안암산      고황산      배봉산
When Seoul was chosen as national capital in 1390, the arrangements of the mountains
surrounding it was a key factor.  In the scheme of five "inner" mountains that should
surround the palace and walled city, three of them are obvious and prominent --
Bugak-san
to the north, Inwang-san to the West and Nam-san to the south (the slight hill where the
Westin Chosun Hotel and the Temple of Heaven now stand served for the center); the city
wall and it's great gates ran and still run along their ridges.   But there is no real mountain
on the east side of old Hanyang, only four significant hills / ridges above and outside of the
East Great Gate [
Dongdaemun] to serve as physical and spiritual guardians.  This was a
glaring weakness that was noted by the great geomancer-monk Muhak-daesa, who had
predicted that when the capital fell the invading army would enter from the east;  this came true.
We can call these four spiritual-guardian hills Seoul's Sadong-san  [4 East Mountains], a
name that fits with Korea's numeric-religious traditions.  They are found just north of and
further east from the
East Great Gate [Dongdae-mun], keeping north of the Cheonggye-
cheon Stream
(that flows east out of downtown and then curves south to the Han River) and west of the
Jungrang-cheon Stream
(that runs south from Uijeongbu, collecting the waters of the northern parts of the
Bukhan-san sub-range, until it merges with Cheonggye-cheon)
.  Their areas were forested and rural
during the Joseon Dynasty, but are completely urban neighborhoods of Seoul today.
The Sadong-san is composed of Nak-san, Anam-san, Gohwang-san & Baebong-san.

Nak-san  (70m) means the home of Gwanse-eum-bosal the Bodhisattva of Compassion.  
This is a long ridge the curls SE from Bugak-san down to the Great East Gate [Dongdae-mun,
formally named
Heunginji-mun].  It is also known as Cheongryong-san [Blue Dragon Mtn] by
those conscious of the Neo-Confucian
pungsu-jiri [geomantic] layout of old Seoul.

Anam-san (90m) is the home of Korea University (one of Korea's top-10), and hosts the significant
traditional Buddhist temples Gaeun-sa and Bomun-sa.  Nearby it to the SE is the Seonnong-dan,
the site where kings from the Unified Shilla, Goryeo and Joseon Dynasties held ceremonies
intended to coax good harvests from the earth, during which the king himself would plow the
field in front of the altar.  This is now famous as being the site where
Seolleong-tang was
invented during one of these ceremonies, by Royal order -- this is the popular soup with
calcium-rich broth made by boiling cattle bones for a long time, than adding strips of beef
and noodles.  Rice and small slices of green onion are added at the table.  

Gaeun-sa [Awakening-Transfer Temple] was founded in 1396 by the great geomancer-monk
Muhak-daesa, under the initial name Yeongdo-sa, as part of his design for reconstruction of
Hanyang as the new capital for Joseon.  It is found partway up Mt. Anam's southern slope, right
next to the large campus of Korea University.  It was not particularly illustrious in the early days.  
In 1779 the tomb of a favored concubine of King Jeongjong was constructed next to it, giving it
higher status.  it is written that when the prince who became King Kojong was a young boy in
the mid-1800s, he spent a few years here for his education.  In 1921 a new abbot reconstructed
the buildings and built a bell-tower, and it became an education/study- center for the national
Jogye Order, as it remains today.  Gaeun-sa's Main Hall enshrines a Buddha statue from the
end of the Goryeo Dynasty made of cloth covering a frame that was then covered with many
layers of lacquer -- unusual.  Its Three Spirits Hall is entitled a Chilseong-gak on its signboard,
following the common pre-20th-century tradition.
Gohwang-san (150m) is the home of KyungHee [Gyeonghui] University (another of Korea's top-10),
giving it a famously beautiful campus; and flanking that, the Hanguk University of Foreign Studies
(HUFS, Weidae) and the Korea Advanced Institute of Science and Technology (KAIST).
It also hosts two medium-size urban Buddhist temples, Gwanbul-sa
(headquarters of the Gwanbul Sect,
in Imun-2-dong)
and Yeonhwa-sa of the Jogye Order (right behind the KyungHee University Hospital).
Baebong-san (105m) is a public city Park to the southeast of the other two.  
It doesn't host any temples or shrines that I know of.
Gohwang-san with KyungHee University