The Blackfriar, whilst not the oldest of pubs (although 105 isn't bad) it is pretty unique.
Even the flat iron shape of this his grade II listed building is impressive, but what's inside is even more so.
Built in 1875 on the site of a Dominican friary that existed here in the 1200s. It was was transformed into an art nouveau experience in 1905 . The decor was designed by architect H. Fuller-Clark and artist Henry Poole, both committed to the free-thinking of the Arts and Crafts Movement. Depictions of jolly friars drinking and feasting appear everywhere in the pub in the copper, plaster and marble sculptures, mosaics and reliefs.
This one is easy to find, right opposite the entrance to Blackfriars Station (and a short walk from St Paul's).
And if the sun is shining (hmm) there is outdoor seating.