Vintage police motorcycles used to escort the UAE's Founding Father Sheikh Zayed at official events are on display in Abu Dhabi. The distinctive red bikes helped guide processions involving Sheikh Zayed in the late 1960s, before he united the emirates to form the UAE in 1971. Abu Dhabi Police are showing part of the historic fleet at the Sheikh Zayed Heritage Festival. The Police Legacy Department is educating visitors about the growth of the Abu Dhabi force since its formation in 1957. The annual event, which celebrates the rich culture of the Emirates dating back centuries, runs until February 20 in Al Wathba. Other exhibits on show include documents detailing treaties with British troops from the 1600s and a painting of the Fortress of Bidiya in Fujairah. A significant letter written by Sheikh Shakhbut bin Dhiyab, then ruler of Abu Dhabi, in the early 1800s is also on display. Military medals and the first one-dirham note are on show. The dirham was introduced in 1973 and the first coin was minted in the 1980s. Cash notes called the “external rupees” or “Gulf rupees” printed in India were used in the UAE before the dirham. The Gulf rupee notes had the same design as the Indian currency but were a different colour.