Radical Islamist preacher Anjem Choudary proposed converting Buckingham Palace into a mosque, jurors were told.
The London-born extremist, who faces 10 years in jail for supporting so-called Islamic State (IS), suggested that the British monarchy and "idols" such as Nelson's Column would be abolished under Sharia Law.
In a video entitled Khalifah Vs The World, Choudary even shared his thoughts about the bathing habits of the Queen and the cleanliness of Londoners, the court heard.
"There are surveys they say that there is more fecal matter on the typewriter than there is in the toilet in the city of London," he said.
"Why? Because people don't clean themselves. They say 'oh look these Muslims clean themselves', of course we do.
He continued: "I once gave a talk and I said Queen Elizabeth used to have one bath a year. I gave this talk in a church and there was a woman there at the front, an elderly lady, and she kind of shrieked at me. She said: 'that's a lie, she had two baths a year'.
"Two baths a year okay, fair enough, twice as much, still doesn't make it a lot, does it, a year? Doesn't make it that clean."
Giving evidence at the Old Bailey, Choudary clarified that he was referring to Elizabeth I and not the current monarch.
He told jurors that he would deliberately "bait" mainstream media in order to win a platform to spread his message of propagating Islam around the world.
Choudary said he gave between 60 and 70 interviews in the months after IS leader Abu Bakr al-Baghdadi declared a Caliphate in June 2014.
Asked about his controversial approach, he said: "My own style is to speak the truth whether people like it or not. Because there are so few people talking about these topics, it leaves a vacuum.
"I would use that as a vehicle for the wider explanation. If it was about stoning an adulterer, I would use it to talk about social systems. I would use that as a platform to pass on my message."