This beautiful Palladian  mansion at Basildon Park in a wonderful position above the River Thames was built in 1776-83.  It fell on hard times early in the 20th century and was rescued and restored by Lord and Lady Iliffe and is now filled with fine pictures and furniture.  
The interior has notable delicate plasterwork, an elegant staircase and unusual Octagon Room.  The early 19th century pleasure grounds are currently being restored and there are waymarked trails through the extensive surrounding parkland.