Tycho Brahe built his observatory underground to stop wind sway

Astronomer Tycho Brahe built Uraniborg, an above-ground observatory on the Danish island of Hven, equipped with the most precise naked-eye astronomical instruments of the era — decades before the telescope existed.

Rather than pursue further refinement of the instruments — building bigger, more finely calibrated devices to try to compensate for a platform problem — Brahe identified that the actual source of imprecision was structural, not instrumental, and addressed the building rather than the tools.

In 1581, Brahe built a second observatory, Stjerneborg, sited mostly underground and anchored into the solid stone beneath the island's sandy topsoil, eliminating the wind-driven sway that had corrupted Uraniborg's readings. He complemented the rigid platform with a methodology of running isolated, independent observing stations so the same celestial event could be measured more than once and cross-checked against itself, combined with his own systematic error-correction techniques.

Moved the instruments underground onto solid rock, removing the sway that no calibration could fix, and cross-checked readings between stations.

Wind sway moved instruments during observation, corrupting readings.

Underground construction eliminated sway by anchoring in solid stone.

Stable platform let instruments reach their full precision.

Cross-checking independent stations further reduced error.

When a tool is accurate but results are off, check the environment it operates in; fixing the platform can beat upgrading the tool.

The combination of a physically stable platform and cross-checked observation methodology pushed naked-eye star-position accuracy to within roughly one arcminute, a roughly 20-fold improvement over anything achieved before him — a precision record that stood for decades and was achieved entirely without a telescope, which wasn't invented until nearly three decades later.