Why Thessaloniki for a city break?
Thessaloniki is Greece's second city and, by most accounts, its most interesting — a multi-layered city of Byzantine churches, Ottoman mosques, Roman monuments and an extraordinary food culture that Greeks themselves regard as the finest in the country. Where Athens has the Acropolis, Thessaloniki has 15 centuries of Byzantine history: the White Tower on the waterfront, the Rotunda (a 4th-century Roman mausoleum, later a Byzantine church, later an Ottoman mosque), and 15 Byzantine churches that collectively received UNESCO World Heritage status in 1988.
From London and several UK airports it's around three hours twenty minutes — direct flights from London Heathrow and Gatwick, with good connections from Manchester and Edinburgh. Thessaloniki Macedonia Airport is 16km from the city (bus X1, €2, 45 minutes, or taxi €25). The city is significantly cheaper than Athens and far less visited by international tourists — a complete meal with wine at one of the city's excellent restaurants costs around £15-20, and the hotels are excellent value. Go in April to June or September to October: the summer heat can be extreme, but the outdoor food culture on the Ladadika waterfront is excellent in warm weather.