The Dublin Castle which came into existence in 1204 was made for the purpose of defence. Dublin has nearly always been an important trade centre. A major catastrophe took place here in Dublin, in the year 1348, when thousands of people died in the coming decade because of the Black Death which was a plague that ravaged the whole of Europe. As the times went by, Dublin kept growing and rising higher and higher. The 16th century conquest by the Tudors brought in a new dawn for Dublin. The city became an important centre for administrative ruling in Ireland. The Trinity College was invented in 1592 by Queen Elizabeth I, in an attempt to make Dublin a fully Protestant City. The greatest of the city’s architecture dates back from the 18th century, when the city temporarily became the second largest city in the whole of the British Empire and the fifth largest in Europe. Some of the popular buildings dating to this time are, the Custom House, Four Courts, Grafton Street and Temple Bar. This did not have to undergo the Georgian renovation unlike the other architectural pieces. The Merrion Square, Royal Exchange and the Parliament House were also built up in the 18th Century.