Temple Bar is the only surviving gateway into the City of London erected in 1672 at the behest of Charles II to replace a previous timber structure which had survived the Great Fire but was falling into disrepair. The new gateway was designed by Christopher Wren.
Nowadays, you can cross the gateway from St. Paul’s cathedral to a very cool new square…
…where you can find an analematic sundial in one of the facades:
Location: Temple Bar (map)