The Tomb of Leonidas has an impressive edifice (12.5m × 8.30 m), probably dating back to the late 5th century BCE. It was made of massive limestone and its interior was divided in two connected chambers. The eastern chamber was 3.15 meters long, had the form of a pronaos (vestibule) and was ornate with columns. Until today, the use of the edifice has not been verified.It is believed to be a cenotaph, while many researchers share the opinion that it is the temple of Karneios Apollo.
Although there is no indication on the correlation between the temple and the legendary king of Sparta, according to local tradition and the travel writer Pausanias, the remains of Leonidas were transferred and buried there. It is because of this, that the locals believe it to be the tomb of Leonidas. Pausanias also mentions that annual games were hosted here to honor the memory of the Spartan king.
References:The ancient Argos Theater was built in 320 BC. and is located in Argos, Greece against Larissa Hill. Nearby from this site is Agora, Roman Odeon, and the Baths of Argos. The theater is one of the largest architectural developments in Greece and was renovated in ca 120 AD.
The Hellenistic theater at Argos is cut into the hillside of the Larisa, with 90 steps up a steep incline, forming a narrow rectilinear cavea. Among the largest theaters in Greece, it held about 20,000 spectators and is divided by two landings into three horizontal sections. Staircases further divide the cavea into four cunei, corresponding to the tribes of Argos A high wall was erected to prevent unauthorized access into the theatron and may have helped the acoustics, but it is said the sound quality is still very good today.
Around 120 CE, both theaters were renovated in the Roman style.