The castle of Virtsu belonged to vassals of the feudal state Bishopric of Ösel-Wiek - Western part of nowadays Estonia as well as part of Saaremaa and part of Hiiumaa. It was built in 1430 by Uexküll noble family and destroyed already in 16th century. Now the ruined walls are few metres high, but it really looks that there is almost nothing. That's because grass and bush is growing on the ruins.
Reference: Virtual Tourist
Built around AD 90 to entertain the legionaries stationed at the fort of Caerleon (Isca), the impressive amphitheatre was the Roman equivalent of today’s multiplex cinema. Wooden benches provided seating for up to 6,000 spectators, who would gather to watch bloodthirsty displays featuring gladiatorial combat and exotic wild animals.
Long after the Romans left, the amphitheatre took on a new life in Arthurian legend. Geoffrey of Monmouth, the somewhat imaginative 12th-century scholar, wrote in his History of the Kings of Britain that Arthur was crowned in Caerleon and that the ruined amphitheatre was actually the remains of King Arthur’s Round Table.
Today it is the most complete Roman amphitheatre in Britain.