The town core is about 300 m above sea level. The highest elevation in the main town of Usingen is the Hohe Berg ("High Mountain"), 414 m above sea level.
In 1207, being on the outskirts of the Usinger Land, it passed into the ownership of the Counts of Diez, who had acquired this Imperial estate in exchange for Mainz-Kastell (fort).
A Nassau castle – in 1326, the Counts of Nassau had acquired the Usinger Land by pledge, and by 1405 for good – on the site of today's Christian-Wirth-Schule (school) and a wall with five towers protected this small weaving town in the Middle Ages.
It is likely that Usingen was granted town rights in the 14th century.
As of 1659, the Counts resided in the castle, now converted into a stately home with a lovely garden, and from 1688 to 1744 the Princes of Nassau-Usingen lived there.
One prominent personage in Usingen's history was Fürst (Prince) Walrad. When Nassau-Saarbrücken lands were being divided up on 31 March 1659, Count Walrad got the Usinger Land. He governed for 43 years and was a respected commander, among other things General field marshal of the Netherlands under William III of Orange. He was a decisive factor in making Usingen the way it is today, since after the Thirty Years' War and the three town fires in the 17th century – with their attendant drop in population – he settled Huguenots in the town and had the New Town built.
Another personage worthy of note was the violinist August Wilhelmj. He was made an honorary citizen of Usingen on 31 March 1876 on the occasion of his last concert in the town of his birth – Usingen. He was born here on 21 September 1845. The house where he was born stood at the lower end of the Rathauspassage, now called Wilhelmjstraße after him. On the lot where the house where he was born stood, where a bank building now stands, a memorial stone with a plaque recalls the important violinist.
Usingen was until 1886 the seat of an Amt and thereafter, until 1972 a district seat. The scant industrial development in modern times could not even be strengthened by the railway connection that came in 1895. Usingen has been since the time of the Reformation a school town: Latin school until 1817, teachers' college from 1851 to 1926, Christian-Wirth-Schule (Gymnasium) since 1926 – today together with many other kinds of school.
As part of municipal reform, the communities of Usingen, Eschbach, Kransberg, Merzhausen, Michelbach, Wernborn and Wilhelmsdorf merged in 1972 into the town of Usingen. Even after losing its function as district seat (Usingen district was merged with Obertaunus district to form the Hochtaunuskreis with its seat at Bad Homburg) Usingen is more than ever the midpoint of the Usinger Land.
In the middle of downtown Usingen is Usingen's stately home, the Usinger Schloss. The home's exact origins have yet to be fully explained. It is assumed that it was built in the 14th century as a castle under Johann I of Nassau-Weilburg. Prince Walrad had a new stately home built on the castle's site in 1660–1663. The architect Friedrich Joachim Stengel (1694–1787) remodelled the Usinger Schloss into a Baroque residence between 1733 and 1738 as instructed by Princess Charlotte Amalie, Prince Wilhelm Heinrich I's widow. In 1873, a great fire destroyed the Schloss, which was afterwards built anew. Today it is used as a Gymnasium (Christian-Wirth-Schule). Bordering right on the Schloss is the Usinger Schlossgarten, the stately home garden.
Another great fire in 1692 destroyed the so-called Usinger Oberstadt (Upper Town). The overlord at that time, Prince Walrad (1635–1702) gave orders for its prompt reconstruction. Symmetrical rows of houses, which still form the townscape now, were built, and along the Obergasse (Upper Lane) appeared representative buildings. The so-called New Town's heart was shaped by the Hugenottenkirche with what is nowadays the old marketplace. Benedikt Burtscher was the building master of the church, built in 1700 and showing in its building style certain commonalities with the well known church at La Rochelle. After the Huguenot church fell out of use with the union of the Lutheran Protestants and the Reformed Church, it was soon converted into a school. Today, however, it houses the Usingen library. On the upper floors are found many places where concerts and gatherings can be accommodated. The wedding room is a favourite place for couples to plight their troth.
Climbers use the steeper walls for training.
The Hattsteinweiher near Usingen is the only bathing lake in the Usinger Land. In summer, when the weather is good, it is the centre of attraction for many visitors from the Taunus and the Frankfurt Rhein-Main Region.
Usingen is home to a ground station with satellite dishes and various other antennas run by T-Systems. After the Second World War, during which the property was used as an aerodrome, a shortwave transmission station was built here. In 1979 came the first big parabolic antenna. Meanwhile, the station now houses more than 90 antennas, among them three dishes measuring 19 m across.