Many homeowners dread receiving their property tax bill, and almost all grumble about how high it is. But for Ottawa’s most expensive houses, the bills are much higher, topping out at about $650,000 for Rideau Hall, residence of the Queen’s representative in Canada. Fortunately for the occupant — former Canadian astronaut Julie Payette — Canadian taxpayers pick up the tab.

In Ottawa, property taxes are calculated at about 1 per cent annually of the estimated value of a house. Anyone is free to look up the assessment on any house. (The Governor General’s residence, with its 79-acre estate, was assessed in 2016 as being worth $65,249,000.) The assessment determines a homeowner’s share of property taxes until 2020, when new assessments will be done.

The highest-assessed houses are occupied by the political elite and foreign diplomats. Yes, in addition to paying the property taxes on residences owned by the Canadian government, taxpayers foot the property tax bill on the residences of foreign diplomats. The Vienna Convention on Diplomatic Relations exempts official residences from municipal real estate taxes; Canada and 191 other countries are signatories.

And one note about the top of the list. Records at city hall show that in the past four years, some houses increased by millions while others fell by millions. Inexplicably, the biggest change was in the assessment on the rundown and currently uninhabited former residence of prime ministers at 24 Sussex. It was assessed to have increased in value by more than $5 million. We have no idea why.

Here, the top 10 highest-assessed houses in Ottawa.

Rideau Hall: Regal Grandeur
2012 assessment: $61,924,000
2016 assessment: $65,249,000

The Governor General’s residence reputedly cost $82,000 to build in the 1860s. Today the property known as Rideau Hall is valued at more than three times as much as any other house in Ottawa. Much of the value of the property is in its surrounding woodlands and gardens, which cover 79 acres. Higher land values probably explain the assessment increase in 2016.

Residence of the U.S. Ambassador
2012 assessment: $19,765,000
2016 assessment: $19,815,000

The expansive residence of the U.S. ambassador on Lisgar Road was built in the early 1900s for Warren Soper, founder of the Ottawa streetcar system, who requested his own streetcar shelter outside the house. The shelter is still there. Little change in assessment suggests stagnation in high-end real estate prices between 2012 and 2016.

French Embassy and Residence
2012 assessment: $13,062,000
2016 assessment: $17,406,000

This handsome art deco building at 42 Sussex houses the French embassy and the ambassador’s residence. Its pristine condition contrasts with the dilapidated, currently unoccupied Canadian prime minister’s residence next door. Built of Quebec granite in the late 1930s, its prime location on the Ottawa River probably explains the sharp increase in property assessment from 2012 to 2016.

The PM’s Fixer-Upper
2012 assessment: $9,673,000
2016 assessment: $15,369,000

No one of sound mind would buy this property. The historic house at 24 Sussex Drive was formerly home to prime ministers of Canada but is in such bad shape that Prime Minister Justin Trudeau lives in a very large “cottage” nearby on the grounds of Rideau Hall. The federal government is undecided on whether to replace or rebuild the house. (Either way, the cost to taxpayers will probably be more than $30 million, the government estimates.)

The Most Dramatic House in Rockcliffe
2012 assessment: $17,720,000
2016 assessment: $14,816,000

The Vatican’s envoy to Canada lives in “undoubtedly the most dramatic house in Rockcliffe.” That’s according to a booklet produced by an architectural conservation advisory committee of the village of Rockcliffe. The booklet was published in 1982, but it may still be true.

Eye-Catching Opulence
2012 assessment: $14,263,000
2016 assessment: $12,488,000

Probably no private home in Rockcliffe ever set tongues wagging as much as this one, which mixes glass and copper-coloured materials and defies neighbourhood tradition. Even several decades after it was built, it still contrasts sharply with the heritage architecture of many 19th- and early-20th-century houses in the area. The house has almost two acres of land, which is a good size in Rockcliffe and adds to its value. Still, its assessment fell by more than $1.7 million between 2012 and 2016, indicating weakness in demand for the priciest houses.

Modern House, Traditional Style
2012 assessment: $11,078,000
2016 assessment: $9,740,000

Built little more than a decade ago, this is a Rockcliffe house in the traditional style of smaller, older neighbouring houses. Located on Manor Avenue, this house has cathedral ceilings throughout the ground floor and 12,500 square feet of living space. After a house-warming party when the house was built, a guest gushed: “It is like a palace, really. A lot of guests were likening it to an old English manor. But it is a very new English manor.”

Converted Historic House
2012 assessment: $9,649,000
2016 assessment: $8,886,000

Many old houses lack space. Many new ones lack character. This Rockcliffe house on Soper Place combines the best of old and new. The owner knocked down most of an old house but kept parts of it and integrated the old stonework into a state-of-the-art modern mansion. Lots of windows allow light to flood in everywhere.

Rothwell Heights Stunner
2012 assessment: $5,348,000
2016 assessment: $5,589,000

Located in Rothwell Heights, this modern stone house would probably be worth at least $2 million more if it were in Rockcliffe. And the neighbourhood is just as tranquil and leafy as Rockcliffe. The house is on a quiet cul-de-sac with views across the Ottawa River to Quebec.

Leafy Seclusion in Kanata
2012 assessment: $6,456,000
2016 assessment: $4,457,000

This house in a residential suburb near Earl of March Secondary School has more privacy than any other on our list: 11 acres of land ringed with high evergreen hedges that hide the main house from view. While it’s far from downtown Ottawa, the house is close to the city’s technology hub. It’s difficult for assessors to value such a property, since there are no sales of comparable houses nearby. (Before you shed a tear, note that the assessment drop of almost $2 million saves the owner about $20,000 annually in property tax.)