Strictly speaking, in a home the threshold is a strip of wood, or stone, on the floor that you cross as you pass through a door way.
I'm being a bit more generous here and including the door jam.
In period homes you will often have walls that are incredibly thick by today's standards. In this case, over 300mm thick. This presented me with an opportunity add a bit of dynamism to what is typically an ignored element in a room. I decided to use a somewhat random array of lines to keep it from becoming too severe because, as with most homes of this age, perfection and straight lines can be jarring compared with the relative imperfection inherent in the original building materials.
Granted it can seem somewhat controversial to introduce such a forward looking approach to a doorway in a period home but my client loves it. She has her own unique, informed style - we discussed abstract expressionism at our first meeting - and was keen to try something more interesting when the opportunity arose. As you see from the picture, taking an opportunity can pay off beautifully.