Riding The River:  From Westminster Pier, you can board a boat that will take you along the river to the Tower (or to Greenwich, if you prefer), with a crew member describing points of interest along the way. Most (if not all) of these boats will offer you seating either inside or outside, depending upon whether or not you want that "fresh air view" and whether or not you brought your sweater. It’s a nice way to get from point to point without the tube or a bus.

Several companies operate from Westminster Pier. Prices are reasonable for this alternate form of transport.

Did You Know?  The Thames is a tidal river and London experienced a number of major floods over the centuries until the completion of the Thames Barrier (just downriver from Greenwich). Now, the Barrier can be operated to prevent such catastrophes.

Unfortunately (or fortunately?), the completion of the Thames Barrier also ended London’s existence as a major port for ocean-going vessels. This left a large part of the East End docks with nothing to do. Many of the old buildings have been refurbished into high-priced apartment buildings.

Tube:  Westminster or Tower Hill, depending upon your starting point.