Ottawa is the capital of Canada. It is the second largest city in Ontario and the fourth largest city in the country. The Centre Block is the main building on Parliament Hill  . It is also the location of several ceremonial spaces, such as the Hall of Honor and the Memorial Chamber. The present Centre Block is the second iteration of the building,after the first was destroyed by fire in 1916,and it is one of the most recognizable buildings in Canada. Downtown Ottawa is the commercial and economic centre of the city. Most of the buildings are office towers. While most of Ottawa's high tech industry is based elsewhere, it has a significant presence in the downtown core. The downtown also contains a number of apartments, hotels, and the older single family homes and townhouses along its edges. The National Gallery of Canada is one of Canada's premier art galleries. The Gallery has a large and varied collection of paintings, drawings, sculpture and photographs. Although its focus is on Canadian art, it also holds works by some noted American and European artists. The Rideau Canal is the oldest continuously operated canal system in North America. At the very beginning,the purpose of the Rideau Canal was military, as it was intended to provide a secure supply and communication route between Montreal and the British naval base in Kingston. It remains in use today primarily for pleasure boating, with most of its original structures undamaged. The locks on the system open for navigation in mid-May and close in mid-October. Collections in the National Gallery of Canada are mainly   _  .
paintings and drawings sculpture and photographs works by Canadian artists artwork by Americans and European