Quinto sells second-hand books. I spend a lot of time here and have found some inspiring books over the years, both at Quinto and the other shops on this road. Koenig Books on the corner is good for art books, too.
Behind Markfield Beam Engine is the River Lee which travels from the Chiltern Hills all the way to the Thames via Tottenham Hale. There is a special light along this stretch of the river possibly due to there being about 10 massive reservoirs behind the levee on the other side of the river, offering an amazing sense of space. A great place to walk, cycle and feed the ducks, swans, geese and coots.
The Greenwich Observatory with its green laser beam can transfigure any night sky. If you decide to cross the Thames via the foot tunnel, make sure you look out for the green ray. You can be on one side of the meridian in a minute, and cross to the other side on the next, without even realising it.