David Armitage finds one capital city elevated by a small modern church, and another ruined by 1960s grey concrete

My favourite building is St Brigid’s Church in Belfast – I have to immediately disclose a vested interest in that the bricks used were manufactured by my own company. This small-scale building is a wonderful example of high quality brickwork created out of a very original design. It features an alignment of brick planes that slope at varying angles and curve round the church’s many turrets. These curved walls are one of the distinguishing features of this modern building. The skill demonstrated by the small team of local bricklayers is one of the main reasons why St Brigid’s is such a worthy choice. The building stands as a beacon of hope for the future after the many years of dereliction Belfast has suffered.

The National Theatre on the South Bank is my least favourite building. It is well known and I have chosen it because it is a classic example of new brutalism. It is typical of the genre that ruined so much of London and our big cities in the 1950s and 1960s. The fact is that exposed concrete cladding is ill-suited to the dark grey weather that pervades much of our winter, and it weathers badly with the passage of time, making it look even less attractive.