We loved our 16 day stay at the casa in Casco Viejo. It is what we look for when traveling to different areas. History, culture, great food experiences. Bilbao is a special area with it's own culture and history. The Basque culture is unique and enjoyable.
Casco Viejo is a very densely populated urban area and most of the time quiet through the night. There were a couple of weekend gatherings near our street that were a little raucous. But the street vibe is generally very uplifting. The Tram is a one minute walk. Metro is about a 6 min walk. There is a mammoth market just a 2 min walk away. Markets for fruit and veggies abound. Cafes and restaurants were ubiquitous. Try Bilbao. You will like it.