Somerset House always lays on a couple of free walks each week. The first one is called the 'Old Palaces Tour', which explores the history of the site before the current building even existed.
In recent years this site has been home to a tax office and an art gallery, but in the past it used to house three of the Stuart queens: Anne of Denmark, Henrietta Maria and Catherine of Braganza.
The tour will also include a look inside the usually inaccessible Strand Lane Bath. Guidebooks refer to this as a Roman Bath, but it's now believed to be a water cistern that fed the plants in Somerset House. (Craig has been to see these so-called 'Roman Baths' himself, and written a review on his blog.)
Note: If you're more interested in the architecture then you might prefer their other free tour: Historical Highlights at Somerset House.
Good Grief, Charlie Brown! – 25 Oct 2018 to 3 Mar 2019 – Fans of Charles M Schulz much-loved Peanuts cartoon will want to see the Charlie Brown and Snoopy exhibition at Somerset House.
Skate! — Christmas ice rink at Somerset House – 14 Nov 2018 to 13 Jan 2019 – Somerset House has got the prettiest rink in London, with a huge Christmas tree and festive shopping arcade
The Original Tour — Open-top sightseeing bus – Every day – The Original Tour is one of London's most popular sightseeing buses, and it's also a great way to travel around the capital.
London Bus Tour — open-top sightseeing bus – Every day – This traditional open-top bus tour will take in all the best landmarks and attractions, with a free river cruise and guided walk.
TRS river cruise, from Big Ben to Greenwich – Every day – Spend a leisurely afternoon on a TRS river cruise from Big Ben to Greenwich, and see some of the sights along the river.
Boat trip down the Thames, with City Cruises – Every day – City Cruises offer one-way, return or all-day boat trips between Westminster and Greenwich, stopping off at Tower Bridge.
Roar down the Thames in a speeding boat! – Every day – A trip on a Thames Rocket is something you'll never forget, speeding down the river underneath the London's bridges.
Look for more Royal events taking place in December
Look for more guided tours in December
Here are some more free events in London if you want a cheap day out
Disclaimer: Event details can change at short notice and you should reconfirm everything before making plans