Nothing heralds the arrival of spring in Rome like the first whiff of a blood orange. Vendors cut open the succulent citrus fruits to show off the crimson flesh to shoppers at the Testaccio market near the Aventine hill (Piazza Testaccio, open Mon-Sat, 7am to 1pm) and the Biological Market in Trastevere (Via Cardinale Merry del Val, open the second Sunday of every month). Coffee bars throughout Rome serve freshly squeezed blood orange juice, spremuta, with a touch of sugar. For an exceptional spremuta, swing by Caffè delle Arance, Piazza Santa Maria in Trastevere, 2 (arance means oranges in Italian)....