The summerhouse. This octagonal structure was built on the hill above the grotto and was the final work to be completed (circa 1766). The summerhouse gave John Scott views across the Lea Valley that inspired some of his poetry. In one poem, he wrote:

 

Now where the airy octagon ascends,

And wide the prospect o'er the vale extends,

'Midst evening's calm, intent perhaps he stands,

And looks o'er all that length of sun-gilt lands,

Of bright green pastures, stretch'd by rivers clear,

And willow groves, or other islands near.