Oratorio del Caballero de Gracia is one of the best hidden architectural treasures in Madrid. This church looks small from the outside, but inside it unfolds into a neoclassical temple by Juan de Villanueva, which looks like a Roman basilica.
Among its most noteworthy internal features are the single-piece granite columns, the vault and the sculptures of the Virgen del Socorro, signed by Francisco Elías in 1825, and of Cristo de la Agonía, which, according to studies, was made by Juan Sánchez Barba in 1650. The church belongs to the Caballero de Gracia Eucharistic Association, founded by Jacobo Gratiis (known as the Caballero de Gracia), who was born in Modena in 1517 and who died in Madrid in 1619. It is currently run by Opus Dei.
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.