The tower is one-of-a-kind in terms of engineering design and construction. The 86-foot-tall tapering octagonal tower has a diameter of 32 feet at the base and 15 feet at the observation deck. It was built by the Carlinville Bridge Company for $10,000. The telescope was made by Hollerith & Co. and is 12 feet in diameter. It was shipped to Oregon in boxes and installed on top of the bridge. This unique structure was used until 1914 when a new electric power system was installed and the optical equipment was given to the Lick Observatory near San Francisco. The Portland Observatory is now a museum that houses many rare instruments including a large refracting telescope, a meridian circle, sextant, and other navigation tools. Visitors can see how long rods were used as measuring devices before the modern yardstick came about. In addition, there are exhibits that show how solar eclipses have been observed for centuries. Today, these events are recorded by observers using computers instead. But even though technology has come a long way since the Portland Observatory was built, it's still an interesting look into the past.