To mark 100 years since the start of World War One, St Paul’s Cathedral commissioned artist Jerry Judah’s creation of two crosses hanging either side of the nave. Their almost lichen-like growth is in fact scale models of bombed-out buildings, representing the horrific impact of war on cities. ‘Bombs expose the private, the personal the intimate,’ says Judah. ‘The skin of a building ripped away to show lives ended in a single blast.’ See these and Bill Viola’s ‘Martyrs’ free Monday-Friday at 11.30am and 2.15pm.