According to TychoBrahe.com, Tycho Brahe is best known for inventing various mechanical devices that made the observation of the stars through astronomy easier. These inventions include various observational quadrants used to track the movement of the stars.
TychoBrahe.com explains that the astronomical instruments Brahe created were remarkably more accurate than the others available at the time. Other contemporary astronomers were forced to calculate up to 10 minutes of error in their observations, but Brahe's instruments allowed him to observe accurately to within 30 seconds. According to Wikipedia, quadrants were the inventor's specialty since they allowed astronomers to measure angles up to 90 degrees. Brache's first quadrant is one of the most impressive inventions of his early years due to its small size.
One of Brache's later and most famous instruments is the great azimuth semicircle, an incredible instrument designed to measure both azimuths and altitudes, two particularly complex facets of astronomical observation. The instrument was made of steel and covered with brass. It remains one of Brache's most ornate inventions, featuring the images of three goddesses enthroned on top, each representing a various aspect of the sciences. The reason the great azimuth semicircle is considered so iconic of Brache's inventions is that it can easily be disassembled and reassembled in another location, like much of his work.