The town was built at the meeting point of the Mátra Mountains and the Great Hungarian Plain, on the two banks of the shallow, yet very capricious Zagyva River. Hatvan (meaning sixty) is exactly sixty kilometres far from Budapest, so a lot of people think that the name refers to the geographical location of the town. But the town, at an important crossing point, received its name - according to some stories - during the time of King St. Ladislaus of the Árpád dynasty (1077-1095), when sixty Petchenegs were settled down here. According to another explanation, the name of the town, which appeared for the first time in 1235 as "Hotvin", referred to the name of a distinguished person from the time of the Hungarian Conquest.
People have lived in the area of the town as far back as the Neolithic Age. The Bronze Age discoveries in the Strázsa Mountains are outstandingly valuable relics. The period is known as "Hatvan culture" all over the world, after the town. Diets and partial diets were held in Hatvan three times during the Middle Ages. The so-called "clamorous" diet was held here in 1525, when in the shadow of the Turkish threat the gentry relieved the palatine of his position, and elected István Werboczy instead. The fortress of Hatvan, weakly defended with banks and fences, could not prevent the expanding Ottoman Empire taking the town under its authority. It only escaped Turkish rule in 1686, but in 1715 it is already registered as one of the six towns of the county.
The magnificent Baroque buildings of Hatvan were built in the 18th century, under Antal Grassalkovich. Grassalkovich, originally from the gentry, who became one of the richest noblemen in the country, built several palaces all over Hungary, beginning in the 1740's. According to the custom of contemporary noblemen he created a library in each of his castles. He had a strong influence on Hungarian palace architecture, and his Baroque palaces are usually described as in the "Grassalkovich style". The one in Hatvan is his last. Built between 1754 and 1763, it is the best preserved of his palaces. The Palace has a central projection, two storeys and 32 rooms. A balcony is supported by columns and figures above the main entrance. The attic above the cornice is typical of the "Grassalkovich style", and a characteristic cupola towers over it. In 1867 the castle became the possession of the Hatvany-Deutsch family, the members of which offered considerable financial assistance for "aesthetic aims and for the purposes of public health". Many famous personalities, leaders in literature and the arts, visited the Hatvany-Deutsch family, among them Thomas Mann. He refers to his visit in his novel "Doctor Faustus".
The Roman Catholic St. Adalbert Church, built in Baroque style between 1751-1755 is another building of strikingly high artistic merit. Standing in the main square of Hatvan, the Kossuth Square, this building is also a testimony to the Grassalkovich inclination to build. Hatvan's Town Hall, one of the most beautiful buildings of the town, is also located on the main square. Built in modern style in 1910, the edifice uses some of the walls of a 12th century Premonstratensian monastery and of an 18th century Capuchin cloister. An ornamental well with a lion decorates the square in front of the building.
The Lajos Hatvany Museum includes outstanding collections of fine art, local history, archaeology and folk art, while the Gyozo Moldovay Gallery inside the Grassalkovich Cultural Centre contributes occasional exhibitions of high standard to the cultural life of the town.
Another interesting and attractive reminder of the Grassalkovich era is a Baroque style manor farm on the northern perimeter of Hatvan, in Gombospuszta. The yard is divided into three. The one on the north side was used for horses, the one in the middle for mixed grain and fodder, and the one on the south side for cattle. The farmstead is surrounded by a Baroque stonewall; the gates from the street are ornamented with statues.