Brahe's mural quadrant was one of the largest astronomical instruments of its time. Each degree could be finely divided and accurately read, giving Brahe's observations the greatest accuracy before the advent of telescopic astronomy. The portrait of Brahe is painted onto the wall pointing toward the slit in the wall through which heavenly bodies were viewed. He is portrayed beneath portraits of his liege-lord and in front of a cross-section of his castle Uraniborg. Notice the astronomical instruments mounted on the roof, meeting rooms on the main floor, and an alchemical laboratory in the basement. Notice too that an observer looks through the quadrant's sights as one assistant calls out the time from clocks and another records the data.