Typical of them are Thaewang and Janggun tombs.

30,000 cubic meters of stone were used in the construction of Thaewang tomb. Over 2,430 square meters of its surface and 78 square meters of chamber are covered with trimmed stones.

Janggun tomb is 34 meters long and wide and 13 meters high with 7 layers piled up with well-trimmed rectangular granites. Huge granites were placed at its base and each of them is one meter wide and high and 6 meters long.

Those tombs, believed to be built 1700 years ago, still keep their original appearances.

Masonry was also developed in the period of Koguryo.

It can be well evidenced by the mausoleum of Kogukwon (A.D. 331-371), the 21st king of Koguryo, and three tombs in Kangso.

Every well-trimmed stone fits together with no slightest gap in the chamber of the mausoleum which was built in the mid-4th century, and no deformation has been observed from joints of walls, ceiling compage, etc. in chambers of three tombs in Kangso.

Different artistic skills like mural paintings in the big and medium tombs in Kangso, world-known masterpieces, were applied to decorate inner walls of tombs in the period of Koguryo.