Crucuno dolmen is one of the most well known dolmens in the Brittany. The rectangular chamber is about 4 metres by 3.5 metres, covered by a single massive capstone which measures over 7 metres in length, perched on top of 9 support stones, with easily enough room to stand upright inside. The enormous capstone is 7.6 metres in length and weighs about 40 tons. Unfortunately, a century or so ago, a house was built right next to it, and this has destroyed all but the last pair of entrance passageway uprights and their capstone. This passageway was recorded in the last century as being 20-25 metres in length, leading away towards the southeast.
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.