A stunning architectural marvel often compared to Sydney's opera house, the Elbphilharmonie is a concert hall and performance space designed by the Pritzker Architecture Prize-winning Swiss architecture firm Herzog & de Meuron. As soon as it opened in 2016, it became an instant architectural icon thanks to its wave-like rooftop and glass façade. Luckily, you don't need tickets to a show to enjoy the striking space.

A public viewing platform is open to everyone and offers breathtaking, 360-degree views of the city and the harbor – a particular highlight for recent visitors. While admission to the viewing plaza is free, you do need a ticket to enter. Advance booking is available and recommended by recent visitors, though a booking fee of 2 euros (or about $2.25) applies. Reviewers also recommended taking a harbor cruise to admire the building from the water.

The Alter Elbtunnel (also called the Old Elbe Tunnel, St. Pauli Elbe Tunnel) is a pedestrian, bike and motorist tunnel (though cars are not permitted), which travels underneath the River Elbe. It connects central Hamburg to the southern side of the river. Opened in 1911, the tunnel was built to serve the port and shipyard workers as a connecting route between the Landungsbrücken and Steinwerder piers. It became a tourist attraction when the "new" Elbe tunnel opened in the 1970s. It has been undergoing renovation for the past several years.

While walking through the quarter-mile-long tunnel, take time to look at the tile reliefs that line the walls, which portray starfish, dolphins and other creatures. Past travelers enjoyed the experience of walking beneath the river and taking in the great view from the opposing side. Others said it provides an interesting photo opportunity, though there is little else to do.

Planten un Blomen, which translates as the very imaginative Plants and Flowers, spans over 100 acres and is a favorite among locals and travelers. Referred to as "Hamburg's green lung," it is home to various themed gardens, including a rose garden, Mediterranean terraces and one of the largest Japanese landscaped gardens in Europe. Planten un Blomen offers much more than the eponymous "plants and flowers." There are playgrounds, mini-golf, an ice rink in winter and a roller rink in summer, and even life-size chess games. There are also several cafes and food kiosks.

Many past visitors said the park is a relaxing place to unwind and highly recommend touring the Japanese garden. Others said the park is well-maintained and a worthy stop even in the offseason.

All-night revelers finish up their partying at the Sunday morning St. Pauli Fischmarkt (Fish Auction Hall and Market) and early morning shoppers get a head start on the day. Not only are there stalls brimming with fresh fish and other goods, there's also steaming hot bratwursts, free-flowing beer and even an energetic band to keep the jovial atmosphere alive. It's also one of those uniquely Hamburg attractions, one which has been an institution since 1703. If you sleep in (or you're just getting to bed after bar hopping), you'll miss out on the Fischmarkt; it's open on early Sunday mornings only.

Recent visitors who knew what they were in for say the scene is fun and festive, while those looking for a traditional market were a bit disappointed. Reviewers described the scene as merry, with many comparing it to Oktoberfest.

The red brick buildings of the Speicherstadt (Warehouse District) used to shelter the city's imports – coffee, spices, silks – which were carried fresh off the boats in the harbor. In 2015, Speicherstadt became Germany's 40th UNESCO World Heritage Site. Today, this area full of neo-Gothic buildings, mostly constructed between 1883 and the late 1920s that are fun to see on foot. Though there are a few attractions within the area, including Miniatur Wunderland and the International Maritime Museum, it mostly attracts visitors in search of photo ops and a picturesque stroll. Popular photo spots include the Wasserschloss (or "water castle") at the end of Holländischer Birdge and Fleetschlösschen, a former customs booth.

Recent visitors call the area magical and recommend taking a canal tour if you can. A few reviewers said it's worth visiting at night when the area is beautifully illuminated.

Hamburg's Reeperbahn once rivaled Amsterdam's Red Light District for its sex trade, but times have changed (slightly). Located in St. Pauli, the Reeperbahn is a nightlife hub, still notorious for its corridor of sex shops, strip shows and brothels, though there are plenty of other non-X-rated activities and sights, from dive bars to the Beatles monument (the Beatles made their mark in Hamburg). St. Pauli is now almost better-known for its huge live-music scene, with clubs, bars, theaters and music venues. The annual Reeperbahn Festival in September brings in around 25,000 people to hear live music.

Recent Reeperbahn visitors found the area interesting to see, with plenty of music and pubs to check out. Others warned of potential pickpockets.