The most expensive object on earth

The venerable old Beeb has produced an interesting article on the most expensive objects in the world. The initial contention is that the proposed Hinkley Point C nuclear power station in the UK may be the most expensive single object ever built, although of course this depends on the definition of "object", and whether one considers a power station to be one object or an amalgamation of various objects.
The construction costs alone of two-reactor Hinkley C project, if built, is expected to amount to some $26 billion, although Greenpeace estimates that, with financing and other costs, the total might reach $35 billion (costs throughout are in US$). This is certainly an extraordinary sum, but does it make it the most expensive object on earth, as Greenpeace claims?
To put this in context, the world's tallest building, the Burj Khalifa in Dubai, cost a paltry $1.5 billion. Heathrow Airport Terminal 2 cost an estimated $3.4 billion. The Large Hadron Collider on the France-Switzerland border cost about $5.8 billion. The eastern span of the Oakland Bay Bridge in San Francisco cost $6.5 billion. Even a hypothetical reconstruction of the Egyptian pyramids would only require about $1 - $1.5 billion in today' money.
But none of these come close to the cost of a nuclear power station. Comparisons are difficult: the last nuclear plant in Britain, Sizewell B, was built back in 1995, at a cost of about $5 billion in today's dollars, and there have been no new nuclear plants built anywhere in Europe this century. The published costs associated with nuclear power stations built more recently, in places like China and India, are considered to be of doubtful reliability.
The only projects that are even in the same ballpark as Hinkley C include: the $21.6 billion London Crossrail railway system (if that can in fact be considered a single object); the refurbishment of the Grand Mosque in Mecca, Saudi Arabia, which is reported to be costing around $23 billion (although this too stretches the definition of "object" somewhat, as it also includes things like road and rail links, etc); the Hong Kong International Airport, which cost about $20 billion back in 1998, or around $29 billion in today's dollars; and Chevron's Gorgon liquefied natural gas plant on Barrow Island in Australia, which cost a mind-boggling $37 billion.
And, finally, if we stretch the "in the world" part of the definition a little, the International Space Station had a price tag of no less than $110 billion. Even a multi-reactor nuclear power station, such as the four-reactor project planned by Turkey, or the six-reactor plant South Africa is thinking of, might have difficulty outdoing that as a pricey single object.