(CNN) -- What makes a city "cool"? If it means being loaded with atmosphere, charm, great food and nightlife, yet ignored by the bulk of travelers, then Lisbon deserves consideration as Europe's coolest capital. Here's why. 1. Nightlife that can outlast Madrid's If you think Madrid stays out late, try a night out in Lisbon. Lisbon: color equals cool. The city is less about heaving clubs and more about a roving nocturnal flow that ends (maybe) when dawn rises over the Tagus River. The main action is in the Bairro Alto, where more than 250 appealing bars line a web of streets between graffiti-plastered walls. Next is the riverfront, in the hip neighborhood around Cais do Sodré railway station. Typical of the offbeat flavor here is the converted brothel Pensão Amor ( Rua do Alecrim 19, +351 21 314 3399 ) where ace cocktails accompany erotica and DJ sets. Capping a Lisbon night are pre-dawn traffic jams at Santa Apolonia docks -- they...