The Guggenheim in Bilbao is definitely worth a visit. The city has improved no end since the arrival of the museum but still not the prettiest execept alongside the river next to the museum. But unless there is a particular exhibition on of interest, the outside of the museum will suffice as it is the star of the show.  Walk round it and watch the light and shadows play on this incredible structure. If you love this then you also have to see  Marques de Riscle, a vineyard with modern hotel (expensive) which has been designed by Frank Gehry. Found in Rioja about a 2 hour drive from Bilbao it stands out like a beacon amongst the vines and set against a very old Riojan village. Entry fee to the Guggenheim is €8 which includes a pre-recorded guide (various languages). There are also 2 restaurants serving excellent food and a self service cafe on the ground floor.