Four World Cities - which is greatest?

Laurie Taylor wants to know which of these four cities is the planet's greatest: Istanbul, Mumbai, New York or London. The big debate is on Radio 4 tomorrow morning (Monday 12 July) at 0900 but we want your opinion now. Leave a comment here on the blog or tweet using the hashtag #GreatestCity, then - here's the important bit - come back to the blog during the programme and join a live chat with other listeners and contributors to the London Season (we're hoping, for instance, that London expert Tony Travers from LSE will be able to join us). See you there!

Steve Bowbrick is editor of the Radio 4 blog

• Listen to the Greatest Cities Debate at 0900 tomorrow morning and to the other programmes from the season on the London: Another Country page.
• The picture is a press photo of Scutari in Istanbul during the early twentieth century, from the Library of Congress collection via the Wikimedia Commons.