Shoal Tower is a Martello tower

Martello tower

Martello towers are small defensive forts built in several countries of the British Empire during the 19th century, from the time of the Napoleonic Wars onwards....

 located in the harbour (Confederation Basin) of Kingston, Ontario

Kingston, Ontario

Kingston, Ontario is a Canadian city located in Eastern Ontario where the St. Lawrence River flows out of Lake Ontario. Originally a First Nations settlement called "Katarowki," , growing European exploration in the 17th Century made it an important trading post...

, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, directly opposite Kingston City Hall. It is one of four such towers built in the 1840s to protect Kingston's harbour and the entrance to the Rideau Canal

Rideau Canal

The Rideau Canal , also known as the Rideau Waterway, connects the city of Ottawa, Ontario, Canada on the Ottawa River to the city of Kingston, Ontario on Lake Ontario. The canal was opened in 1832 as a precaution in case of war with the United States and is still in use today, with most of its...

. Cathcart Tower

Cathcart Tower

Cathcart Tower is a Martello tower located on Cedar Island in the St. Lawrence River, off the eastern shore of Fort Henry in Kingston, Ontario, Canada. It is one of four such towers built in the 1840s to protect Kingston's harbour and the entrance to the Rideau Canal...

 on Cedar Island, Shoal Tower in the Confederation Basin, Fort Frederick

Fort Frederick (Kingston)

Fort Frederick is a historic military building located on Point Frederick on the grounds of the Royal Military College of Canada in Kingston, Ontario, Canada. Its construction dates to 1846 and the Oregon crisis. The fort consists of earthworks surrounding a Martello tower...

 on the grounds of the Royal Military College of Canada

Royal Military College of Canada

The Royal Military College of Canada, RMC, or RMCC , is the military academy of the Canadian Forces, and is a degree-granting university. RMC was established in 1876. RMC is the only federal institution in Canada with degree granting powers...

, and Murney Tower

Murney Tower

Murney Tower is a Martello tower in Kingston, Ontario, Canada, whose construction dates to 1846 and the Oregon crisis. Officially designated as Murray Tower, the locals called it Murney Tower, as it was built on Murney Point, which was owned by the Murney family at the time. They have since...

 were part of the same strategic improvements. Although 16 Martello towers were built in Canada, only 11 are still standing, four of them in Kingston.

Built in 1847, this limestone tower is 11 m high and 16.5 m in diameter . The guns of Shoal Tower defended the approaches of Kingston Harbour. A dispute between Great Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 and the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 over the boundary between British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

 and Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 that threatened to lead to war and to the invasion of Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 (see Oregon crisis) prompted their construction. Eventually Shoal Tower was abandoned.

It was designated a National Historic Site of Canada in 1930, and is part of the Kingston Fortifications National Historic Site.