A schematic of Tycho Brahe's subterranean astronomical observatory Stjerneborg (Stelleburgi).

This plan-view schematic shows the observatory bounded by a square wall with semi-circular extensions on each side, the entrance on the left lies in the direction of the nearby palace Uraniborg. Annotations are:

   * A = Entrance with steps leading down into the main workroom (B) and (D) and (E), above are three lion sculptures and Latin inscriptions
   * B = The main Workroom containing (P) and (V) and passages to (C), (F), (G), and (Q)
   * C = chamber with large equatorial instrument
   * D = chamber with elevation and azimuth quadrant
   * E = chamber with armillary sphere
   * F = chamber with elevation and azimuth quadrant encompassed by a steel square
   * G = chamber with sextant for measuring distances
   * H = stone pillars one with a ball on top, the other angled, situated at the near side
   * I = stone pillars one with a ball on top, the other angled, situated at the far side
   * K, L, N and T = large balls, with conical covers, used for mounting instruments
   * M = Stone table, shown with sundial in Willem Blaeu's drawing
   * O = bed of Tycho Brahe
   * P = fireplace
   * Q = Tycho's assistant's bedroom
   * S = beginning of an underground passage to Uraniborg