Hackney is now synonymous with urban cool, but its oldest building dates back to the 13th-century – a medieval tower, which is all that remains of the church of St Augustine. The original church was said to have been built by the wealthy Knights Templar, who probably didn't travel to the sound of cocunut shells being bashed together by lackeys but who did own much of the land in Hackney. When they fell out of favour (around 1308), the lands passed to the Knights of St John (who later founded the St John Ambulance service – the only way of getting emergency medical transport before the NHS arrived), and the church was renamed St John-at-Hackney (demolished in 1798).
It’s a steep walk to the top of the tower, but you’ll be rewarded by impressive views across Hackney. The odd art exhibition is held here and it's part of London's Open House but you can also visit 2-4.30pm on the last Sunday of each month. While you're here, pop your head into the nearby 'new' St John-at-Hackney, built by James Spiller, who was influenced by neo-classical architect and collector/hoarder, Sir John Soane.