The Prince of Wales has given a lecture on Islam and the environment at Oxford University's Sheldonian Theatre.
Before giving his speech, Prince Charles visited the new £65m Oxford Centre for Islamic Studies and had a tour the building.
The prince's visit on Wednesday marked the 25th anniversary of the Oxford centre, which he has been a patron of since 1993.
After the lecture Charles joined a reception for invited guests.
Amre Aiad, one of the architects who has been working on the centre's new building, said: "We are very pleased because this building is a remarkable building and it's honourable to have him appreciating it and recognising the value of it and coming to see it before it's finished."
In 1993, the prince gave a speech entitled Islam and the West at the inauguration of the centre's Distinguished Lecturer Programme.
Since then, annual lectures at the centre have been given by world figures including former president of South Africa Nelson Mandela, former United Nations secretary-general Kofi Annan and Sonia Gandhi, leader of India's Congress Party.
The centre aims to encourage a better understanding of the culture and civilisation of Islam and of contemporary Muslim societies.
The centre's new building includes a minaret, dome and a chapel.