Described by UNESCO as a masterpiece of Gothic architecture, the Cologne Cathedral or the Kölner Dom is an awe-inspiring world heritage site. The construction of this Gothic cathedral started in 1248 and took 632 years to complete. When the church was finally completed in 1880, it was one of the world's tallest buildings. The Dom stands an imposing 157 meters (505 feet) high and while climbing one of the towers may be quite an endeavor, the view from the top is definitely worth the effort. Located within the cathedral is the Treasure Chamber, which is home to significant religious artifacts, including the hooked staff of Saint Peter. The Cologne Cathedral is a well-known historic landmark that can't be missed.

In the mid-19th Century, there was a bridge connecting the two banks of the Rhein near the Kölner Dom. This bridge was jokingly known to the inhabitants of the city as the Muusfall - the Mousetrap. At the beginning of the 20th Century, it had to give way to the Hohenzollern Bridge, a half-timbered arch bridge that was designed to carry the railway. Although the bridge was destroyed in 1945 during the last few days of World War II, it was later rebuilt and is most notable for the thousands of 'love padlocks' that adorn the railings. One of the most photographed landmarks in Cologne, the arches of the bridge light up the night in a beautiful sight to behold.

Museum Ludwig had its beginnings in 1976 when Peter and Irene Ludwig donated 350 works of contemporary artists. Works by artists like Warhol, Lichtenstein and Segal line the halls of this museum, which focuses primarily on 20th Century art. Visitors can study works of the Russian Avant-Garde from 1906-1930 as well as pieces on permanent loan by Pablo Picasso. Museum director Kasper König is interested in creating a dialogue with visitors; he encourages people to engage with the museum rather than being mere passing observers, so come equipped with your thinking caps! On the first Thursdays, the museum is open till 10p.

The Cologne Zoological Garden, also called the Kölner Zoo, is Germany's third oldest zoo and remains one of the city's top attractions. It was founded in 1860 and the elephant house was the first building to be opened. Over the years, the zoo has grown in size and is well known for its conservation efforts. You'll discover animals from around the world, including Big Cats and primates. Make sure you check out its great exhibits like the elephant park, the aquarium and the Rainforest Hall.

Designed by Oswald Mathias Ungers and opened in 2001, the neo-cubist Wallraf-Richartz-Museum is the perfect backdrop for exhibitions of post-15th Century European art. You'll find a stunning collection of Medieval works as well as neo-impressionist and impressionist art. Visit the second floor to see the Print Room which holds priceless drawings, including sketches by Leonardo da Vinci. There is also an onsite shop and cafe. This museum is a must-visit for all art lovers.

The imposing tower of the Great Saint Martin Church, also called Gross St Martin, watches over the crossroads in the Altstadt of Cologne. This Roman Catholic church was first home to an abbey founded by Benedictine monks. Steeped in history, the church of Great Saint Martin Church, with its clover-leaf choir, still bears witness to the Hohenstaufen period. Built between 1151 and 1240, the church has remained a part of the Cologne Old Town skyline since the Middle Ages. The quarter around the church is called the Martinsviertel.

The former headquarters of the Cologne Gestapo, EL-DE Haus is now the NS Documentation Center of the City of Cologne. Founded in 1979 after the city council passed a resolution, it is the biggest provincial memorial place for the victims of the Third Reich in the nation. Get a glimpse of the social and political life in Cologne during the regime of the National Socialists through their permanent exhibitions. This award-winning museum offers an in-depth insight into the physical and administrative conditions of that era.

Located next to the Cologne Zoological Garden, the Flora und Botanischer Garten Köln is a beautiful green expanse covering 11.5 hectares (28.4 acres). The garden was founded in 1863 and was designed for different landscaping styles, including German, English and Italian Renaissance. The entrance is grand, with iron gates, a palace-like reception building and an impressive fountain. There are also various greenhouses, including a tropical house, cactus house and a sub-tropical house. Strolling through this gorgeous park is the perfect way to spend a sunny afternoon.

The Dreikönigsschrein (shrine of the Three Holy Kings), the largest shrine of the Middle Ages, shines out from behind the high altar of the Kölner Dom. The shrine was made by the famous goldsmith Nikolas von Verdun after the relics were brought to Cologne in 1164 by Archbishop Raimund of Dassel. The 220 centimeters (86 inches) shrine has been accessible to visitors and pilgrims in its entirety since its restoration in 1973, having been severely damaged during an attempt to move it to safety during the French occupation. A golden wonder, the shrine boasts of elaborate reliefs depicting figures of apostles, evangelists, prophets and also Biblical scenes. A breathtaking sight, the shrine is a revered reliquary.

The St. Gereon's Basilica is said to be the most beautiful medieval church in Cologne. Though the structure was mentioned in records dating back to 612, the church as seen today was built between 1151 and 1227. St. Gereon's Basilica is known for a unique architectural style where the nave is topped by a decagonal oval dome. The church was dedicated to St Gereon at a later date in June 1920. Archaeological evidence has suggested the existence of an earlier church dating back to the fourth century. The original site was supposedly referred to as Ad Sanctos Aureos i.e. the church of the Golden Saints.