What a difference a day makes!

Compared with its weekday bustle, the City is deserted on a Saturday, but for a few window cleaners, scaffolding erecters and.... a party of Marketors with their Blue Badge Guide, Kym Dewey, seen here walking past (probably) the oldest church in London, St Bartholomew the Great. It was so quiet we could stand in the middle of most roads and even the ducks could saunter with impunity past the intimidating faces of the Goldsmiths' leopards.

I had never seen the Roman amphitheatre under the Guildhall Art Gallery before - I love the way that as you walk up the entrance "passageway" the crowd cheers your arrival in the arena. And the wooden drainage channels look decades old rather than two millennia. (Now I know why the navy used oak. And did you see "Time Team" last night on a huge related archaeological dig in Gresham Street, with its water pumps? It was a great day for history buffs.)

Kym explained the origin of the word "role" for a part in a play, and of the word "float" in the Lord Mayor's procession - if you don't know, ask someone who was on the walk. She showed us the monument to the two men who collected and published Shakespeare's first folio of collected works, and explained why Barts Hospital is where it is. She took us to the most poignant Memorial of Heroic Self Sacrifice in Postman's Park (adults and children who died saving other people's lives) originally established by the artist G F Watts, recommissioned in 2009 after many years' dormancy.

A big thank you to Jean-Francois Dor for organising the walk and to Dan Doherty for finding us the Eastside Inn at Smithfield which was willing to open on a Saturday lunch time for us and lived up to Marketors' standards of excellence and value.

If you are interested in learning your way around the City I recommend buying a jigsaw puzzle of a street map of London. You can order them with any postcode as the central piece of the jigsaw, which extends roughly 2 miles North-South and 3 miles East-West. Various versions of modern and ancient maps and a satellite view are available. I have recently bought one with Mansion House at the centre. Just Google "jigsaw puzzle maps" and you will find several suppliers. I bought mine from Firebox for £19.99 + p&p.