For some reason, this Basque Country, so close to the border of France is not bragged about constantly. After a year abroad and visiting beautiful places all over the world, this city makes the top 5 for sure.
With a history of an industrial city, it’s hard to believe there is so much beauty. If you appreciate cool architecture, it is definitely a place you want to visit. The mixture of ancient and modern architecture took my breath away, on every street. I still can’t decide if it’s more beautiful at night or during the day. Another perk it’s probably the best lit city that I have ever been to.
As for activities, you probably need to go the Guggenheim museum (that sweet as building on the right). It is not free but definitely worth every penny. 
We spent a few hours and barely got through it all. Luckily you can go back and visit the rest in the same day with your wrist band. If you like to venture cities then this is one I would say to get lost in. We started in the Old City, heading towards the food market and kept going. It’s not that big but there is so much to admire. I forgot to mention the estuary that runs in the middle of the city. I can’t stress enough how cool Bilbao is. There are more great museums but the culture was amazing. We were there on a sunny day and it felt pretty perfect honestly. It seemed like everyone was outside, enjoying this secret paradise.