Richard Marsden has an account of a journey with friends to Oxburgh Hall in Norfolk, an inward-facing great house owned by and continuously inhabited by the Bedingfield family since its construction in the 15th century. (Cf. Bashing Secularism: Oxburgh Hall.)
The most important feature of the house (now open under the auspices of the National Trust) is the priest's hole construced by St Nicholas Owen. The pictures are from Bashing Secularism; above you can see Richard climbing down the first part of the hiding hole. Below you can see how the priests had to duck down and then enter the main part.
There are probably other hiding holes constructed by the saintly carpenter that have not yet been found.
Richard also has an earlier article devoted to St Nicholas Owen.