Tomb Of Theseus

I'd really appreciate it if someone could give me information on this topic, as I have not been able to find any.

The back story is that, during the Battle of Marathon, the Athenian soldiers reported seeing a man, bearing the appearance of Theseus, appear out of nowhere and fight alongside the Athenians. Afterwards, they sought to find the remains of the Hero and put them in a place of honor within the city. On the island where Theseus was said to have died, they found what appeared to be the remains of a man, interpreting it to be the remains of Theseus because of their unusual appearance. They were taken back to Athens where they were entombed in the center of the city, and there they also built a sanctuary to Theseus for the oppressed and powerless. Now, the problem is that those bones were not those of Theseus. They were those of a pre-historic animal, as the island contained fossils. So I have 3 questions:

1- Is that tomb to "Theseus" still in Athens and, if so, do we know where it is?

2- Where are the actual remains of the Hero if we know?

3- Does there exist a more credible tomb to the Hero?

Thanks.

1- Is that tomb to "Theseus" still in Athens and, if so, do we know where it is?

I have never heard of any such structure still existing. Athens has experienced a variety of almost total reconstructions since Antiquity. The current city bears little resemblance in layout or content to Classical Athens. Furthermore, during the last few decades of the Roman Empire, and onward into Byzantine times, the agents of the State Church did a fairly thorough job of obliterating any remaining 'pagan monuments'.

2- Where are the actual remains of the Hero if we know?

Probably either destroyed or covered up by several yards of accumulated buildup from the last 1,500 years, built over by some later structure – perhaps beneath what is now a parking lot or carwash or something.

3- Does there exist a more credible tomb to the Hero?

Highly doubtful.