Nyon is a very nice city located on the borders of Lac Leman (kak Lake of Geneva). It is reached in twenty minutes from Geneva with regular trains.
Steep streets with old houses lead up from the lake to the white Chateau. The Chateau can be visited but was closed for restauration when I was there (Jan 2004). From Nyon you can make boat trips to Evian and Geneva. The view accross the lake is spectacular on a clear day you see the Mont Blanc.
At the time of the Romans the city was named Julia Equestrius. It has many features demonstrating that it was once an important Roman colony.
As you walk down from Place Perdtemps you may spot an amphitheatre, discovered during some building works for appartments that would never be built.
One of the major summer events is the Palo Festival de Nyon.