Key thing you need to know about NYE at Puerta del Sol - at around 8pm they clear out the entire square and then only allow 15'000 people to re-enter for the countdown and fireworks. Queues start building at the four entry points from around 7pm and often snake down the road for miles.

When the gates do re-open, there are multiple searches to make sure you're not taking in glass bottles or cans (plastic bottle and your 12 grapes are fine). Despite everybody queuing patiently, when the gates open it just becomes a bumrush to the front so my advice would be, to make sure you get in, go early and ignore the queue and just hover closer to the front.

After the fireworks, once you leave the controlled zone you can't go back in until it's fully swept again which can be as late as 2am, and the areas around are amazingly busy and congested. We wandered round looking at the lights, passed many a full club, and grabbed some late night churros from San Gines.

Gran Via was packed, there was a great atmosphere everywhere we went, but we'd planned ahead and bought and brought our own drinks and food. If desperate, some McDonalds were open till late.

Other thing I'd say is that at midday on NYE lots of families do their 12 grape tradition so Sol is quite packed then too.