Plaza Unamuno
Climb the Mallona stairs from Plaza Unamuno to Parque Etxebarria for the great views.
Casco Viejo
Walk through the seven streets of the Casco Viejo.
Aste Nagusia
Beginning the first Saturday after August 15th and lasting for 9 days is Aste Nagusia / Semana Grande, the city's fiesta holiday. An interesting time to come, but be prepared for lots of noise, music, street theater and events, with firework displays in the evening. Details from the tourist office in Teatro Arriaga.
Go kayaking or rent a boat from Bilbobentura (http://www.bilbobentura.com/en) a company that rents out kayaks on the bank of the river nervion.
Artxanda Funicular
Take the Artxanda Funicular, again for the views.
First Saturdays Flea Market
Dos de Mayo Street transforms every first Saturday into a flea market selling antiques, books, and second hand clothes.
Walk along the river.
open air concert
In the summer see an open air concert at the Kiosko del Arenal El Arenal Parque across from Plaza Arriaga. The stage was built in 1923, and renovated in 1985.
Doña Casilda Iturrizar Park
Walk through Doña Casilda Iturrizar Park, admiring the ponds and gardens, next to the Fine Arts Museum.