Tower Bridge

Two great stone towers rise from the river, joined high in the air by walkways and low down by a roadway that splits and lifts when a tall ship needs to pass. This is Tower Bridge, the blue-and-white Victorian crossing beside the Tower of London, and it is probably the most recognised bridge on the Thames, even to people who have never set foot in the city.

First, a common mix-up worth clearing. Tower Bridge is the grand one with the towers and the lifting road; the plain crossing just upstream is London Bridge, which despite the famous song is far less dramatic. Many visitors photograph one while naming the other, so it is worth knowing which is which before you arrive.

The bridge was a feat of its age. It was completed in 1894, after years of work, to give the crowded east of the city a new crossing that could still let tall ships reach the busy docks upstream. The answer was a bascule bridge — a roadway in two halves that swing upward like a drawbridge to open a gap for shipping.

Behind the stonework, the bridge is really a steel machine in disguise. Its Victorian Gothic towers and walkways are a decorative skin over a steel frame, designed to look solid and historic while housing the powerful machinery that raised the road. For its day it was a bold marriage of engineering and theatre.

The bascules still lift today, though now for leisure and scheduled traffic rather than cargo ships. The lift times are published in advance, and catching a raising — the road parting and swinging up while crowds watch from the banks — is one of the small free spectacles of London. It is worth timing a visit around one.

You can also go inside and up. The Tower Bridge Exhibition takes you into the high walkways between the towers, where a glass floor lets you look straight down on the traffic and the river far below. The same ticket leads to the old engine rooms, where the original steam machinery that once powered the lifts is kept and explained.

From those high walkways the views run for miles. Upstream the city's modern towers crowd the skyline; downstream the river bends away toward the old docklands. It is one of the better high vantage points in the centre, and quieter than the famous paid viewing platforms elsewhere in the city.

Down at river level, the bridge frames its neighbours. The Tower of London sits right beside it on the north bank, so the medieval fortress and the Victorian bridge appear together in the same view, and the riverside walks on both banks give you long, free angles on the whole scene.

The colour scheme is more recent than the bridge. The blue and white you see today was chosen in the twentieth century; for its early life the bridge was a more sober brown. Small changes like this are a reminder that even a structure this famous has been touched up and rethought over the years.

A few practical notes. Walking across the road deck is free and takes only a few minutes; going up into the walkways and engine rooms needs a ticket, best booked ahead in summer. Check the lift schedule online before you come if seeing the bridge open is on your list.

The bridge sits between two banks worth exploring. The south side leads to riverside walks, food markets, and modern attractions, while the north side brings you to the Tower and the old City, so the crossing makes a natural hinge in a day of walking the river.

The bridge has played its part in the life of the river and the city, opening tens of thousands of times since it was built and appearing in countless films and photographs. It was designed when London stood at the centre of a vast trading empire, and it had to serve the working river as much as impress the eye.

From the south bank, a riverside walk gives the classic view, with the bascules and towers reflected in the water on a still day. Early morning and the hour after sunset, when the bridge is lit, are the best times for photographs without the thickest crowds on the deck.

Stop in the middle of the deck for a moment, with the towers rising on either side and the river running beneath your feet. The bridge has carried more than a century of traffic and stood for the whole city in countless photographs. Cross it slowly, and it is more than a route; it is one of the set pieces of London.