>>ulian na liu in hong kong also speaking to carrie gracie. o on to twitter, go to carrie's account @bbc carrie. you can see her 25 tweets on why tiananmen still matters. >>> the mayor of venice along with 30 other people has been arrested over corruption allegations. mayor george ji orsoni is being claimed over claims of bribery during the public tender process for new flood barriers built to protect the city. almost 80 of these barriers will be used to shut off the venice lagoon in the event of rising sea levels and storms. the city can suffer from flooding several times in a year. alan johnson spoke to me about those arrests just a short time ago. >> we're talking here in this flood barrier project of a really coloss sol scheme, hugely important, $7 billion worth of engineering, the biggest project of its kind ever undertaken in italy and for about three years now, the financial police here in italy have been looking into what they believe is the mishandling of some 20 million euros which they believe were directed to pay bribes to politicia