The Giant House Spider (Eratigena atrica) is one of the biggest spiders living throughout Europe.
The female body size can reach 18.5 millimetres in length, with males having a slightly smaller body at around 12 to 15 millimetres in length.
The female leg span is typically around 45 millimetres.
The leg span of the male is highly variable, with spans between 25 to 75 millimetres being common.
This species can bite humans, usually when they try to catch or remove it with their hands.
The bite is not very painful and an occasional moderate local swelling disappears within a few hours.
I found this large spider on the ceiling of one of the bird hides near the EVOA Visitor Centre.
EVOA Visitor Centre area, Tagus Estuary Nature Reserve, Portugal, 7 October 2021