Ottawa is a city rich in historic buildings with interesting architecture, particularly along the downtown Wellington Street strip that is home to many federal government offices.

The core of the nation's capital features the Gothic revival style of Parliament Hill and its related buildings, the Beaux Arts columns of the Wellington Building and the Art Deco styling of the former Bank of Montreal building.

But with history comes another unpleasant reality: many buildings in Ottawa are in rough shape and some in prime locations remain vacant or underutilized.

Some are undergoing massive repairs to fix structural issues, while others have been vacated because of asbestos in the walls, poor insulation and plumbing issues.

Public Works and Government Services of Canada is in the midst of its latest five-year plan to revitalize the Parliamentary Precinct district.

Pricey repairs The cost of three major Public Works projects underway: Building Estimated cost (millions of $) Expected completion date East Block - Northwest Tower repair 13.9 2013 Wellington Building 425 2015 West Block 863 2017

Current repairs are focused on the West Block of Parliament and the Wellington Building at the southeast corner of Wellington Street and Bank Street.

A 2010 audit from then auditor general Sheila Fraser described the West Block — built in 1865 — as needing urgent repair. Fraser said it could face a "total failure" of its heating, cooling and electrical systems in 2013 if work isn't completed soon.

"The stonework has a lot of cracks and is crumbling. There's asbestos in the building. There's major work that has to be done," Fraser said.

To fix the West Block, Public Works had to move workers to other buildings, including La Promenade Building at 151 Sparks St., the former Bank of Montreal building at 140 Wellington St. and the recently renovated 1 Wellington St., next to the Chateau Laurier. Repairs include masonry work, repairing the copper roof as well as the removal of asbestos in the interior.

The West Block and the refurbishing of the Wellington Building are the main components of what Public Works calls its Long Term Vision and Plan for the Parliamentary district.

But other federally owned buildings are also in need of work, are vacant or abandoned, such as the former U.S. embassy at 100 Wellington St., the massive warehouse at 933 Gladstone Ave. and the huge office complex near the Experimental Farm, the Sir John Carling Building.

Public Works is not the only landlord needing to make repairs. The National Capital Commission, which operates the six official residences, also has its work cut out to try and fix its buildings. In 2008, the auditor general found the windows and plumbing at the prime minister's home at 24 Sussex Drive were in poor to critical condition and the Governor General's home at Rideau Hall needed work to its walls, roof and windows.

24 Sussex Drive The prime minister and the NCC have been at odds over repairs to 24 Sussex Drive. (Canadian Press) The official residence of the prime minister of Canada hasn't had major renovations in 50 years. The landlord, the National Capital Commission, estimates work valued at $10 million is needed, including removing asbestos, installing sprinkler systems and fixing plumbing, windows and electrical systems. The NCC wants the prime minister and his family to vacate the building for 12 to 15 months so repairs can be done, but has thus far been rebuffed.

West Block, Parliament Repairs to the West Block are expected to be completed in 2017 at a cost of $863 million. (Sean Kilpatrick/Canadian Press ) Problems with the 146-year-old West Block building include crumbling masonry and mortar joints, asbestos in the walls and outdated mechanical, electrical and emergency systems. The estimated cost to repair and find alternative space during repairs is $863 million, according to Public Works. The building normally houses members of Parliament and their employees as well as committee rooms. Work is expected to be completed in 2017.

Wellington Building The Wellington building sits at Bank Street and Wellington Street in the downtown core. (Paul Jay/CBC) The House of Commons was the primary tenant of the building at Bank and Wellington streets, but it has been vacant since 2010 because repairs are underway to remove asbestos, refit the interior and repair the exterior. Repairs are targeted to be complete by 2015 at an estimated cost of $425.2 million. (Paul Jay/CBC)

100 Wellington St. Public Works said it is exploring options for the future use of the former U.S. embassy, which is vacant. (Paul Jay/CBC) The former U.S. embassy, built in 1931, has been vacant since 1999. In 2001, then prime minister Jean Chrétien approved a $22-million plan to turn the building into a portrait gallery, but the Harper government shelved the plan and further renovations in 2006, arguing the plan was expensive and inappropriate given the number of galleries in the city.

144 Wellington St. Work isn't expected to begin on the former Bank of Montreal until January 2012. (Paul Jay/CBC) Built in the early 1930s, the former Bank of Montreal building is in an ideal location opposite the West Block. Inspections from Public Works report that the building needs reinforcement in the event of earthquakes, masonry repair, window refurbishment and interior upgrades. Renovations are expected to begin in early 2012. The project is expected to cost $99 million.

Sir John Carling Building Public Works said it is considering deconstructing the Sir John Carling Building, but plans to turn the West Annex building over to Agriculture and Agri-Fod Canada. (Google Streetview) The office complex near Prince of Wales Drive was once home to 1,200 bureaucrats, mostly from Agriculture Canada, but 30 years after it opened in 1967, Public Works said its building systems were "poor" and began plans to demolish it. The 431,250-square-foot building has been empty since the fall of 2009. Public Works said it hopes to have a demolition contract in place in 2012. After demolition, the property is to be landscaped.

933 Gladstone Public Works said it would review its own space needs before potentially selling the land after it demolishes the warehouse complex. (Google Maps) Stretching from 933 Gladstone Ave. in the south to the offices of 1010 Somerset St. in the north, this massive warehouse space dating back to the Second World War has been mostly vacant because of structural problems. Public Works said it plans to demolish the building, decontaminate the site and use some of it for its own needs and possibly sell the remainder. Because of its proximity to Ottawa's Little Italy, park space and the O-Train green corridor/multiuse path, community groups have taken an active interest in its eventual fate.