As far as safety goes, there's little cause for concern. Central Madrid is so populated - and so busy at just about every hour of the day and night - that it never seems to carry any "big city" threat. Which is not to say that crime
is not a problem, nor that there aren't sleazy pockets to be avoided. Madrid has a big drug problem, all too evident around the Plaza de España and some of the streets just north of Gran Vía. Drugs, it is reckoned, account for ninety percent of crimes in Madrid, and if you are unlucky enough to be threatened for money, it's unwise to resist.
In recent years parts of the barrio of Lavapíes have also been a focus of night-time criminal activity so it is best to stick to the busier streets here. Be aware that the main routes through the Casa de Campo and the Parque del Oeste have been appropriated by prostitutes and their clients and are best steered clear of at night.
Tourists in Madrid, as everywhere, are prime targets for pickpockets, and petty thieves. The main shopping areas, parks, the metro and anywhere with crowds, are their favourite haunts; burger bars and the Rastro market seem especially popular. Be aware that they often work in groups, and associates will try to distract your attention while your pocket is being picked. Tourists are also obvious targets for muggers and in all areas it is advisable to keep jewellery, watches and cameras hidden, and to stay away from dark, empty streets at night.
Unless they have rented expensive garage space, drivers may well find their cars broken into and the radio stolen. The police are generally fairly sympathetic and will give you a report form for insurance claims. In an emergency, dial 112; English is usually spoken on this number.