Rusting safe in city building

Monday afternoon and back to my interplanetary journeying - Mercury today.  See this post if you don't know what I'm talking about.

After radiotherapy, I spend another hour wandering the streets and alleys of the city, and managed to tick a few more churches off my list.

I visited:

 St Stephen Walbrook.  (Open at the time of my visit.  The former rector of this church, Chad Varah founded The Samaritans, and the original phone is there in a glass case in the church.)

St Mary Woolnorth (Open at the time of my visit.  There seemed to be a small meeting going on)

St Mary Abchurch (Closed at the time of my visit)

St Clement East Cheap (Closed at the time of my visit)

St Edmund King and Martyr (Closed at the time of my visit)

I tried unsuccessfully to find the tower of St Martin Orgar.  I tried several different streets and quite a few alleys, but where was it?

In the course of all this purposeful aimless wandering, in a narrow alley near Cannon St, I came across an old building with a rusting metal structure on the outside.  Upon closer inspection it seemed to be an ancient safe with the back rusted away.  Weird!