The Roman Amphitheater in Trier is designated as part of the Roman Monuments, Cathedral of St. Peter and Church of Our Lady in Trier UNESCO World Heritage Site. The arena, built in the 2nd century A.D. for cruel games with gladiators and animals, had a seating capacity of about 20,000. When you enter the premises you walk through the ruins of the entrance gate. This was used as a quarry in the Middle Ages. The arena itself is surrounded by a protecting wall with openings for animal cages. Underneath the arena is a vast cellar where, in Roman times, prisoners sentenced to death were kept alongside exotic wild animals like African lions or Asian tigers.
References:The Cathedral of Saint Mary Major, often called Lisbon Cathedral or simply the Sé, is a Roman Catholic cathedral located in Lisbon, Portugal. The oldest church in the city, it is the seat of the Patriarchate of Lisbon. The cathedral has survived many earthquakes and has been modified, renovated and restored several times. It is nowadays a mix of different architectural styles.
The site where it stands was the principal mosque of Lisbon when it was an Arab settlement. The construction of the cathedral started around 1150, three years after the city was conquered from the Moors during the Second Crusade. Shortly after the victory the English knight Gilbert of Hastings was named bishop of the city of Lisbon.
One good reason to visit the Cathedral is to visit its charming cloisters located in the back. There are several tombs in the cathedral, the most notable of which is the beautifully sculpted tomb of Lopo Fernandes Pacheco and his wife.