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Models

Cheomseongdae Observatory

Gyeongju, North Gyeongsang · Silla, reign of Queen Seondeok (632–647)

2,188 parts · 21 kinds · 35 steps

Parts by step

  1. Step 1: Baseplate

    16 parts · 1 kinds

    Make a 32x32 base from sixteen 8x8 plates.

  2. Step 2: Courtyard

    258 parts · 4 kinds

    Cover the sandy yard with tan and dark tan tiles.

  3. Step 3: Name plaque

    3 parts · 1 kinds

  4. Step 4: Base

    21 parts · 2 kinds

    A square 24x24 base. Ring the edge with bricks and put walls inside.

  5. Step 5: Base cover

    72 parts · 2 kinds

    Cover with two layers of plates for thick base stones.

  6. Step 6: Course 1

    114 parts · 9 kinds

    Lay bricks around the circle and fill inward so each course holds up the one above. Turn the bricks the other way on every course so they interlock.

  7. Step 7: Base top

    95 parts · 3 kinds

    Cover the top of the base around the body with tiles.

  8. Step 8: Course 2

    117 parts · 9 kinds

  9. Step 9: Course 3

    108 parts · 9 kinds

  10. Step 10: Course 4

    109 parts · 9 kinds

  11. Step 11: Course 5

    101 parts · 9 kinds

  12. Step 12: Course 6

    99 parts · 8 kinds

  13. Step 13: Course 7

    96 parts · 7 kinds

    From here the width shrinks quickly, forming the concave curve of the bottle shape.

  14. Step 14: Course 8

    89 parts · 9 kinds

  15. Step 15: Course 9

    80 parts · 8 kinds

  16. Step 16: Course 10

    75 parts · 8 kinds

  17. Step 17: Course 11

    77 parts · 8 kinds

  18. Step 18: Course 12

    69 parts · 8 kinds

  19. Step 19: Course 13

    57 parts · 8 kinds

  20. Step 20: Course 14

    52 parts · 9 kinds

    Leave the middle four studs at the front open, deep into the body, for the square window. Keep the same opening through course 16.

  21. Step 21: Course 15

    34 parts · 7 kinds

  22. Step 22: Course 16

    35 parts · 6 kinds

  23. Step 23: Course 17

    45 parts · 6 kinds

    In the first course above the window, long bricks span across it.

  24. Step 24: Course 18

    40 parts · 7 kinds

  25. Step 25: Course 19

    40 parts · 8 kinds

  26. Step 26: Course 20

    42 parts · 8 kinds

  27. Step 27: Course 21

    39 parts · 8 kinds

  28. Step 28: Course 22

    36 parts · 5 kinds

    The upper part is a straight cylinder of nearly even width.

  29. Step 29: Course 23

    35 parts · 6 kinds

  30. Step 30: Course 24

    30 parts · 8 kinds

  31. Step 31: Course 25

    37 parts · 5 kinds

  32. Step 32: Course 26

    32 parts · 7 kinds

  33. Step 33: Course 27

    27 parts · 7 kinds

  34. Step 34: Top frame, lower layer

    4 parts · 2 kinds

    Lay two long stones across the top, front and back.

  35. Step 35: Top frame, upper layer

    4 parts · 2 kinds

    Lay two more long stones across them, left and right, to make a 井 (jeong) shape.

About the building

This astronomical observatory was built in Gyeongju during the reign of Queen Seondeok of Silla. About 9 m tall, its cylindrical body is 27 courses of fan-shaped stones. A square window opens on the southeast side; below it the inside is filled with rubble, and above it the body is hollow. A square stone structure sits on top. It is designated a National Treasure.

Model details

Size
25.6 × 25.6 × 29.9 cm high
Difficulty
Medium
Updated
2026-09-24
Set history
Every part and color has a set record since 2020 (Rebrickable 2026-09-24)

Design notes

Proportions from a photo set the body at 20 studs across the bottom, and the body height (about 1.6 times that width) then matched 27 brick courses, so each stone course is one brick course. Each course is a round ring whose diameter comes from the curve in the photo, shrinking from 20 studs at the bottom to 11 at the top. The lower courses are filled inward to hold up the ones above, and the bricks turn direction every course to interlock. The window is four studs wide at the front of courses 14–16, and four long stones form the top frame (jeongjaseok). The curved faces of the fan-shaped stones become the stepped edges of square bricks. Every part passed the automated build check.

References