Sultan Ahmed I was determined to build a mosque that rivaled the nearby Hagia Sophia, and most would agree that he accomplished this task – or, at least, came close. Since the early 1600s, the Blue Mosque has been quite the sight to behold, with an array of domes, semidomes and minarets (or narrow towers). It's also one of the biggest tourist draws in Istanbul.

Visitors say this mosque offers "stunning architecture inside and out." It can, however, get busy, so consider arriving early. And remember, the Blue Mosque is an active religious site, so dress conservatively. Women should wear headscarves, as is custom. If you forgot to bring one, you can borrow one from the mosque.

Nestled within Istanbul's historic Fatih district by the Golden Horn, Istanbul University and the Grand Bazaar, Süleymaniye Mosque is considered one of the city's most impressive Ottoman mosques. Built between 1550 and 1557 after being commissioned by its namesake, Süleyman I, this grand structure features multiple gardens and a large dome, plus high-end finishes like mother-of-pearl window shutters, painted corbels, traditional ceramic tiles and stained-glass windows.

Recent travelers described their time at this mosque as "amazing" and "peaceful," adding that it is just as stunning as the Blue Mosque and cannot be missed. What's more, this attraction is not as central and popular as others like the Hagia Sophia Museum, meaning you won't have to rub elbows with lots of tourists while visiting. But remember, like other religious sites in the area, Süleymaniye Mosque hosts six prayer services every day, so expect occasional closures and dress conservatively. If you forget to wear long pants or pack a scarf to cover your head, the mosque offers loaner coverings at its entrance.

Located within walking distance of must-visit sights like the Blue Mosque, the Basilica Cistern and Süleymaniye Mosque, the Grand Bazaar is one of the biggest and oldest covered shopping markets in the world. It regularly overwhelms visitors with its 60 streets of 5,000-plus shops, each accompanied by an overzealous vendor. Products range from carpets and clothing to art and chessboards, and restaurants, cafes and even two hammams (or Turkish baths) can be found here.

Despite the size and the chaos of this bazaar, shoppers say you'll find yourself strangely at ease with the rhythm of the market, thanks in part to the friendliness of the vendors, who are far from pushy. Remember, though, that Westerners are often quoted higher rates for items here, so come prepared to bargain. Most merchants will drop their rates by as much as 50 percent when a customer refuses to pay full price. What's more, additional discounts are often given to those who pay with cash, although most vendors do accept credit cards.

Taksim Square is a vibrant, modern area located in Istanbul's Beyoglu district. Scores of shops, restaurants and bars fill the surrounding streets, as well as popular hotels like the InterContinental Istanbul and the Grand Hyatt Istanbul. The square also features notable landmarks like the Taksim Republic Monument (Taksim Cumhuriyet Aniti), which commemorates the creation of the Turkish Republic in 1923.

Recent travelers had mixed feelings about Taksim Square. While some said it's a wonderful area to visit, others characterized it as "nothing special," especially when compared to squares like Tiananmen in Beijing and Tahrir in Cairo.

While the area surrounding Taksim Square draws the vast majority of partygoers, the small neighborhood of Ortaköy happily enjoys its less popular status. You won't simply stumble onto this cool enclave; located north of Beyoglu along the Bosphorus, you'll need to take a ferry or a bus from the Kabatas tram stop to reach it. Hopping a taxi will be a necessity in the nighttime, but the journey will be well worth it.

During the day, you can explore the narrow streets that divide a dense array of market stalls and shops. But when the sun goes down, crowded restaurants and bustling bars take over. Ortaköy is a nightlife hub for Istanbul's trendy and wealthy young people, so expect to pay dearly for that breathtaking view of the Bosphorus and your delicious food or drink.