The City of London is actually only a small area east of central London, also known as the Square Mile. (See City of London Boundary Map.) This is the financial and business center of London and where you'll find the suit-wearing bankers and stockbrokers dashing around. The City of London becomes really quiet at the weekend when the workers aren't there. It's well worth a visit as it's full of historical buildings next to modern additions. And, there's loads to do for free.
Don't forget to also see:

© Laura PorterThe Museum of London's mission is to inspire a passion for London. It documents the history of London from Roman times up to today.

© Laura PorterThe Bank of England Museum is a hidden treasure down a side-road, off the Bank of England. The absolute highlight for me is the opportunity to lift a genuine gold bar.

© Laura PorterSt Paul's Cathedral in London sells tickets for visitors but there are ways to visit St. Paul's Cathedral for free. If you are short on time or money, find out here how you can visit St. Paul's Cathedral in London for free.

© Laura PorterGresham College has no students and does not teach courses but is an educational institution of higher learning that exists to provide free public lectures. The free public lectures have been running for over 400 years.
St Olave's Church is a small medieval church, where
Samuel Pepys, London's 17th century diarist, and his wife Elizabeth lie buried. St. Olave's is a peaceful place to listen to music, with a lively lunchtime recital series.

© Laura PorterPrince Henry's Room is one of the few houses in London which survived the Great Fire of London in 1666. The building was once a tavern (pub) and has some original oak panels and an ornate plaster ceiling. It is a private building but is open to the public weekday lunchtimes. This room was equipped in 1975 by the
Samuel Pepys Club with materials illustrating some features of the life and achievements of Pepys.

© Laura PorterThe London Stone is a fragment of a 3,000 year old piece of limestone that for years was considered to be the symbolic heart of London. Its age and original purpose are not known, although it has been suggested that it was the point from which the Romans measured all distances in Britannia.

© Laura PorterThe Gallery was established in 1885 to house and display paintings and sculpture belonging to the Corporation of London. Located in the historic heart of the City next to the medieval Guildhall, the present building opened to the public in 1999. City workers and residents can get in for free after obtaining a free pass from the Gallery (fill out a form and show a proof of address of work/home at the Gallery information desk).
Admission to the Gallery is free on Fridays and after 3.30pm on other days. There are free Friday tours of the Guildhall Art Gallery and the Roman Amphitheatre showing highlights of the Gallery's permanent collection. The tours take place every Friday at 12.15pm, 1.15pm, 2.15pm and 3.15pm. Booking is not needed.

© Laura PorterWhitefriars Crypt in the City of London is the remains of a 14th century medieval priory that belonged to a Carmelite order known as the White Friars. Find out more including where to find it and how to see it for free.

© Laura PorterThe Clockmakers' Collection was begun in 1814 and is the oldest collection specifically of clocks and watches in the world. The exhibition of 1000 exhibits form a sparkling display in a single room off Guildhall Library. It tells the extraordinary story of "The Clockmakers of London" from c.1600 to the present day.
Address: Guildhall Library, Aldermanbury, EC2P 2EJ
Opening Hours: Monday to Saturday, 9.30am – 4.30pm