The box in Beijing
For those who want to play the game Spot the Covert Interception Site, here's a nice picture of a mysterious white box on the roof of the Canadian embassy in Beijing that looks like it would be highly suitable for hosting intercept antennas.
Former CSE employee Mike Frost reported in his 1994 book Spyworld that NSA applied heavy pressure on CSE to place an intercept site in the Canadian embassy in Beijing, and that the projected site even received a codename, Badger.
Frost did not know whether such a site was ever put into operation, but it certainly seems like a plausible possibility.
And, yes, if you're keeping track, the Chinese embassy in Ottawa also has a few mysterious boxes on its roof. It is manifestly untrue that "every country" conducts this kind of operation, but there is no doubt whatsoever that China is among the countries that do.