I just watched the episode again earlier than Inspector Queen's comment you are referencing, the police mention that Buck Nolan's car was found Near Grant's Tomb, which is also near Hamilton Drew's home. They just couldn't place him in it.
So later, when Buck's girlfriend says they drove around, Queen asks if they visited Grant's Tomb. Makes sense to me!
How sad, that you were not born in my time, nor I, in yours.

Haven't seen this for a while so I don't know the context. Is it possible he was making a joke about the person being really old, as in, old enough to have been around when Grant was president?
As I say I don't know about this instance, but I have heard similar jokes in other situations.

I'd have to watch the episode again, but it's probably a reference to Grant's Tomb, a monument in upper Manhattan. And the joke notwithstanding, he really is interred there.