A ‘podium’ – plural ‘podia’ because it’s Latin – is “a platform used to raise something to a short distance above its surroundings“. That was the best definition I could find. It may range from a stand for a conductor or winners of a sporting event to stand on to a projecting lower structure round the base of a higher structure such as a tower. In the Barbican, it is the apparent ground level of the entire estate raised a few feet above the surrounding streets and buildings.

The podium covers so much of the estate that, once you are inside, it is effectively ground level. This new pedestrian level, which is generally 6 meters above street level, extends over 4.8 hectares of the site, in the form of terraces, linked by narrower high walks. The podium seems to be even higher when you lean over one of the balustrade edges to look at the lake or the gardens, which are in fact not at ‘ground’ level but several meters below it.

The Barbican Centre famously has many levels which no-one can follow, but its ‘ground level’ is the below-ground level of the lake and the gardens. This adds to the apparent separation of the estate and the Arts Centre.

In fact, most buildings in the south Barbican area exist at both levels. Just as the traditional terraced London house has a ‘ground’ level at the front onto the street, and a basement which in fact opens at a different ‘ground’ level onto the garden at the back, so most south Barbican terraces have a ‘ground floor’ entrance on the podium, and ‘basement’ flats which magically become garden or lakeside flats. Thomas More House has fine looking flats overlooking the gardens, and Andrewes House has split level flats almost at the level of the lake.

We generally speak of ‘the podium’, but to be strictly correct there are two podia. There is a major split of levels between the north and south Barbican podia. Since the land slopes down to the river, to keep the estate dead flat the podium had to be ‘stepped’ and the north podium had to be built a few meters higher than the south podium.

When the Barbican estate was being planned, Chamberlin Powell and Bon gave several reasons why having podia was an advantage for the site:

• it would separate road traffic from foot traffic
• service traffic could move at road level without disturbing residents
• the space below the podia could be used to accommodate garages and services
• where the windows of flats are forced to look out over roads – even on lower floors – they will at least be well above street level.

The architects cited several precedents for the principle of podium with terraces above. They referred to Carlton House Terrace. They mentioned the old Adelphi as being a complex example of the application of this principle of separating traffic on different levels.

They reported that in October 1958, a delegation of the Barbican Committee (which was the committee of the City Corporation in charge of the development) inspected a redevelopment in the central area of Stockholm, which was adopting the podium principle. They also visited Berlin to inspect the new Congress Hall, which had recently been built by the Benjamin Franklin Foundation. But they found the best example for the complete separate segregation of road and service traffic in a city to be in Venice:

“… where all supplies are carried to the city on canals, while pedestrians walk on pavements which cross the canals by bridges. This segregation has worked admirably for many centuries and there is no good reason why the principle should not be applied equally effectively in the City of London provided sufficient thought is given to the detailed design.”

Chamberlin Powell and Bon recommended the podium arrangement of the new deveopment in their 1959 report to the City Corporation:

“It is highly desirable – if a livable urban environment is to be created for pedestrians – to be able to move about without an anxious awareness of fast moving vehicles and in circumstances where conversation is not drowned by traffic noises. In a residential precinct. It is also particularly important that during the night state of quiet should exist undisturbed, as far as possible, by the noise of commercial motors.”