Since the earliest civilizations, princes and priests have maintained observatories, where by observing the sun, moon, stars, and planets, astronomers could determine the passing of months, seasons, and years, and watch the skies for any changes, which they often interpreted as portents. Remains of these early observatories are found worldwide. Stonehenge is one well-known example.

Of the observatories in use before the invention of the telescope, perhaps the most scientifically produced was that of Tyco Brahe about 400 years ago on the island of Hveen in the Baltic Sea. Johannes Keepler used Tyco's precise sightings of the planets to establish his laws of planetary motion. The first telescopic observatory was that of Galileo in 1609. Galileo's telescope consisted of tiny glass lenses mounted in wooden tubes. The era of big telescope observatories began just over 200 years ago with Sir William Herschel and his metal mirrors, in England. The 20th century has seen a constant growth in telescope size, number, complexity, and performance.

The earliest observatory in North America was likely at Louisbourg in 1750. A number of observatories with modest telescopes were created in Canada in the 19th century, such as the ones in Fredricton in 1851, Quebec City in 1854, Kingston in 1856, and Montreal in 1879. An early observatory in Toronto, under government auspices was devoted to observation of geomagnetism and meteorology as well as astronomy.

In 1933, Mrs. David Dunlap presented the U of T with a 1.88m telescope, and in 1935, the David Dunlap Observatory (DDO) was completed in Richmond Hill, Ontario. Two smaller telescopes have been added, and DDO's research has recently expanded into the southern skies. In 1971, the U of T in Las Campanas, Chili, erected a 61cm telescope. This small telescope was soon the most productive of all Canadian telescopes.

Canada's latest development in optical observations has been the construction of the Canada-France-Hawaii-Telescope (CFHT), on Maura Keo in Hawaii. During the 1960's, several groups in Canada pointed out the need for a larger and more up-to-date telescope. The federal government was sympathetic, and finally decided on a joint undertaking with France and Hawaii. The site, at an altitude of 4200m, is regarded as the best in the Northern Hemisphere. A 3.6m telescope of the most modern design was inaugurated in September 1979. Canadian astronomers from all across the country compete for 45% of the CFHT time; the rest us shared between France and Hawaii. Recent studies have included nearby objects such as Halley's Comet, and Loki, the lava lake on Jupiter's satellite, Io.

Canada has many smaller observatories from coast to coast. Telescopes for instruction and research are found at; U of Montreal, Laval, U of Western Ontario, York U, U of Alberta, U of Calgary, U of British Columbia, and U of Victoria.