Lisbon, capital city and economic epicentre of Portugal. While the rest of the country is still recovering from 2010's slump culminating in the following year's 78 billion euro recovery package from the International Monetary Fund, Lisbon has just about managed to sustain an even keal throughout. Largely reliant on tourism, there's a distinct divide between wealth and poverty that becomes increasingly evident over the course of the five days DiS spends here. While the cost of living is ridiculously cheap compared to the UK, and indeed most of Europe, there's also an exclusivity about some of the more palatial residencies around the city. Five star hotels sit comfortably alongside rows of boarded up buildings and run down businesses. Walk along the quayside and you'll encounter an entirely different world. Plush restaurants and clubs - including the lavish Bica Do Sapato, partly owned by American actor John Malkovich - adorn its walkways, while proprietors and customers yachts sit patiently in the harbour.

Lisbon is also steeped in history, something many of its inhabitants appear to play down. Deemed to be the oldest city in Western Europe, a visit to the city's National History Museum or MUHNAC as it's known locally proves both enlightening and fascinating. Having substantially developed its infrastructure between 1987 and 1998, it's little surprise their transportation network is possibly only second to the technically efficient Germans. Road systems mirror Birmingham's spaghetti junction by design yet prove effective in linking each part of the city while its rail network also leaves most of its European rivals standing, Britain included. Add some of the most breathtaking architecture in the Western hemisphere and it is clear to see why Lisbon is highly regarded as one of the most beautiful cities in Europe.

Which brings us onto our reason for being here. Optimus Alive is currently the largest music festival in Portugal having first opened its gates in 2007. Seven years on, and with a growing reputation for being one of the friendliest, cheapest (weekend tickets with camping cost a paltry £103!) and chilled out events of its kind, it's little surprise punters now flock from all over the world for a piece of the action. As with most European festivals, Optimus Alive has so much more to offer than just a random assortment of bands playing in a confined area. Situated next to the Tejo river in Oeiras on the outskirts of Lisbon and taking place between 12th and 14th July, its partnership with the Lisbon Institute of Science and Technology's Biological research department offers a somewhat unique experience to festival goers. Having established the partnership in 2008, the institute's stall opposite the Heineken (second) Stage offers a "speed dating" service allowing participants to question scientists about various experiments and initiatives currently being undertaken. DiS takes up the opportunity for a lengthy discussion around genetic engineering based on a study involving rib cages in mice that proves equally if not more rewarding than the majority of Optimus Alive's musical fare. Which isn't a criticism incidentally, but more a startling observation that music festivals can be so much more than drinking copious amounts of warm lager from paper cups before passing out to a soundtrack of Kasabian and Mumford & Sons.

Throughout our stay here, the organisers continually stress that Optimus Alive's target audience is overseas - and predominantly British. In many ways rivalling Benicassim in terms of location and line-up, it is an altogether more pleasant experience than what's fast becoming Spain's equivalent of V Festival (or "V by the sea" as one publication described it last year). While some of its headline acts might attract little more than a shrug of the shoulders (Green Day, Kings Of Leon), there's a smattering of excellent up-and-coming artists across its three stages as well as the odd exclusive (Depeche Mode) to boot. Add some of the craziest side-stall games we've ever witnessed - one entitled Love Exxxplosion, which involves couples simulating sex where the object of the game is to burst a balloon strategically placed around their midriff areas - along with a wide range of excellent and affordable food options and the "Loser" Martini bar (2 euros for an extremely tall glass!) and it is easy to forget the reams of corporate billboards adorning the names of the festival's numerous sponsors emblazoned all across the site.

Trawling through the line-up, Friday looks particularly appetising in both the Optimus Clubbing and Heineken Stages if not the Optimus (main) Stage, which offers a fairly predictable list of familiar names. Gold Panda's minimalist techno kickstarts our weekend at the unfeasibly early time of 6pm, and while his obtuse, dub-infused breaks make our feet twitch in time to the music, the sound of Kelly Jones drawling 'Maybe Tomorrow' bleeding in from the main stage makes us want to tear our ears off. Canadian duo Japandroids are a more fervent proposition over on the Heineken Stage, their finely tuned noise rock proving more difficult to knock out of its stride. New songs including one introduced as 'Black Death' sit alongside old favourites such as 'Younger Us' and 'The House That Heaven Built'. By the end, guitarist Brian King is bouncing up and down on the drum riser which in turn sparks a similar response from the audience out front. Win-Win all round then.

Over on the Optimus stage, Two Door Cinema Club draw a large crowd, many of whom are possibly waiting patiently for the headliners yet participate in swaying along to the Belfast trio's jerky angular pop nonetheless. Inbetween times, Portuguese instrumental trio Dead Combo combine traditional influences with folk, surf and even the odd post-rock riff to maximum effect, packing out the popular Heineken Stage to rapturous applause. Back on the main stage, we make every effort to appreciate Green Day's corporate punk rock before quickly realising A) every song sounds the same and B) there's only so many times one can hear a grown man scream "Lisbon, we love you!" before rendering oneself physically sick.

Fortunately, LA collective Edward Sharpe & The Magnetic Zeros are an entirely different proposition altogether. Derided by some over their Hollywood backgrounds and supposed lack of authenticity, frontman Alex Ebert and his assorted band of singers and musicians come on like a stripped down Arcade Fire which brings a communal party spirit to the festival. A rousing 'Home Is Where I Am With You', introduced by Ebert as "a cover of an Of Monsters And Men song" sums up their ethos while 'Come Dance With Me' does exactly what it says on the packet, enlisting several thousand ecstatic punters along the way. Vampire Weekend are also a revelation. As their recent slot at Glastonbury suggested, they've ditched much of the filler associated with second album Contra, instead preferring to go for the jugular with a set that relies heavily on both their debut and recent long player Modern Vampires Of The City. Unsurprisingly, pandemonium ensues when the first chords of 'A Punk' emanate from the speakers, but it is the more refined moments like 'Hannah Hunt' and 'Oxford Comma' that firmly illustrate their new found substance and maturity.

Miami DJ Steve Aoki reminds us of Skrillex and we swiftly move on, which is just as well because a once-in-a-lifetime occasion is about to take place over yonder on the Heineken stage. With proposed headliners Death From Above 1979 pulling out due to illness at the last minute, Marky Ramone's Blitzkrieg featuring Andrew WK have stepped in as last minute replacements. Dismissed by many as cheesy nostalgia, they're a perfect way to end Optimus Alive's first day, drawing on The Ramones extensive back catalogue before cheekily exiting the stage to a soundtrack of WK's 'Party Hard'. Hoarse with singing along and sweaty due to an hour's worth of pogoing, DiS contentedly retires to bed.

The next day, we stumble across a five-piece called Boca Doce who are like a Portuguese take on The Hives. We're really here for Diiv though, who conjure up an exquisite forty minutes worth of swooning psychgaze. It's also bass player Devin Ruben Perez's birthday and after a chorus of 'Happy Birthday' to introduce the set, singer Cole Smith informs the crowd "He thinks he's not gonna get laid on his birthday but we all know that's not right!" Two new songs are aired in between Oshin's more upbeat moments. One of them, 'Dust', sounds like The Cure go chillwave. Finishing on a frantic 'Doused', they're one of the weekend's highlights, even if their set isn't as well attended as some less deserving acts.

Meanwhile over on the Optimus Clubbing stage, How To Dress Well also suffer from the main stage sound bleed that dogged the previous evening's sets. Nevertheless, 'Running Back' still retains a quaint effervescence while 'Struggle' and 'Ready For The World' also blossom amid such adversity. Jurassic 5 are an impressive commodity on the main stage, fusing DJ battles with snippets of Dead Prez's 'Hip Hop' and other assorted classics of the genre. 'Freedom' is dedicated to "political prisoners everywhere" although the biggest cheer, unsurprisingly, is reserved for 'Quality Control', their hit single from 2000 and arguably best known song.

If Glastonbury was the relaunch of Editors mk II, then Optimus Alive could be described as the new line-up's coming of age. Displaying a confident air that seemed to be missing at Worthy Farm, Tom Smith and co. deliver a set deserving of such a high billing, newer compositions such as 'A Ton Of Love' and 'Sugar' toughened up and diligently assured here. It's Depeche Mode though that draw the biggest crowd of the day - if not the entire weekend. Despite making no secret of their apprehension about playing festivals, Dave Gahan and co. seem blissfully at home on the main Optimus Stage. Pirouetting and cavorting his way through the entire set, the frontman's on stage antics only add to the array of musical delights on offer. March's Delta Machine being a timely return to form after 2009's disappointing Sounds Of The Universe, their decision to play a number of songs off the new record within a career spanning set is an inspired one. 'Welcome To My World' and 'Angel' introducing the band as numerous projections appear behind them. A stripped down version of 'Shake The Disease' sung by Martin Gore is monumental, while the closing trio of 'A Question Of Time', 'Enjoy The Silence' and 'Personal Jesus' coupled with a five-song encore culminating in 1987's 'Never Let Me Down' raises the bar to impossibly unachievable heights. DiS is impressed, so much in fact that we decide to head to the bars of Lisbon rather than watch any more music as anything else after Depeche Mode will be a dismal anticlimax.

With the final day looming, Lisbon four-piece Linda Martini mix furious post-rock with a metallic edge not unlike late and most definitely lamented quartet Jetplane Landing. Suitably buoyed, we make our way to the front and headbang profusely in the scorching mid-afternoon sun. Over on the Heineken Stage, Icelandic outfit Of Monsters And Men easily pull that stage's biggest crowd of the weekend. While not exactly celebrated in many quarters due to the plagiaristic nature of much of their output, it's easy to see why they're a perfect festival band given the appropriate setting. Australia may have forfeited the first test of the Ashes just hours earlier but that doesn't stop Tame Impala from turning in an impeccable performance. Cheered on by what seems to be a large Aussie contingent in the crowd, 'Feels Like We Can Only Go Backwards' and 'Mind Mischief' recall the spirit of Woodstock as retold by Kevin Parker. Its the closing duo of 'Desire Be, Desire Go' and 'Half Full Glass Of Wine' that really demonstrate how far Tame Impala's live show has developed these past twelve months. Whereas before such long drawn out jams would have been met with yawns and sighs, they reach newly defined skyscraping heights this evening, making them a tough act for anyone to follow.

Anyone else but Phoenix that is. If ever a band could wholeheartedly claim to have achieved their current status the hard way, as one of the biggest alternative rock bands in the world, it's Versailles' finest. Watched by another ridiculously huge crowd, tonight's set expectedly focuses on current record Bankrupt! and its predecessor Wolfgang Amadeus Phoenix. Nevertheless, there's still welcome run outs for early singles 'Too Young' and 'If I Ever Feel Better', the former in particular creating a frenzied response out front. Although much of the attention is aimed towards vocalist Thomas Mars, the realisation Phoenix are such a tight musical unit doesn't go amiss. Closing their set with a triumphant 'Rome', it feels like there's little point in headliners Kings Of Leon bothering to follow suit. That they do makes us and several thousand others shuffle away for the homelier confines of the Heineken Stage instead. Which is just as well as Band Of Horses' desolate Americana brings our weekend and Optimus Alive to a befitting close.

With the organisers beaming afterwards at this year's event being a resounding success, one can only speculate as to what they have in store next year. What is for sure is that Optimus Alive is an ultimately fulfilling experience, and even though still relatively infant (this was only the seventh year) compared to its more established peers, its ascendance up the league table of European festivals is surely imminent. Obrigado e adeus!