The Varbola Stronghold was the largest circular rampart fortress and trading centre in Estonia in the 10th-12th centuries. The first record of Varbola is written by Henry of Livonia, who mentions the Castrum Warbole being besieged in 1211 for several days by Mstislav the Bold of Novgorod. The conflict was resolved with a payment of seven hundred Marks.
During the Livonian crusade Livonian Brothers of the Sword invaded the territory and the people from Varbola asked for the terms of peace. The terms offered by Livonian Brothers of the Sword were accepted by Varbolians, but later the people of Varbola became the subjects of the King of Denmark. On the basis of the Danish Census Book the estate surrounding the Varbola trading center remained a possession of the Lode family, nobility of Estonian origin at the time. The Varbola stronghold lost its importance only in the second quarter of the 14th century, after having played in important part in the anti-Christian and anti-German St. George's Night Uprising of 1343.
In the 16-17th centuries the stronghold was used as a cemetery. The first known fort plan dates from 1786 and was drawn by Ludwig August von Mellin. Archaeological excavations at the site have been undertaken in 1938-41, 1953 and 1974. Among the archaeological finds were dice made of bone.
Parts of the ruins of the 580 metre long and 8-10 metre high limestone wall of the fortress stand still this day. The long gateways with multiple gates were built to defend the entrances. In these sections higher defensive towers were erected. There was a 13 metre deep well in the middle of the fortress and the territory held about 90 structures with furnaces for accommodation built with limestone floors and foundations.
The Palazzo Colonna is a palatial block of buildings built in part over ruins of an old Roman Serapeum, and has belonged to the prestigious Colonna family for over twenty generations.
The first part of the palace dates from the 13th century, and tradition holds that the building hosted Dante in his visit to Rome. The first documentary mention notes that the property hosted Cardinal Giovanni and Giacomo Colonna in the 13th century. It was also home to Cardinal Oddone Colonna before he ascended to the papacy as Martin V (1417–1431).
With his passing, the palace was sacked during feuds, and the main property passed into the hands of the Della Rovere family. It returned to the Colonna family when Marcantonio I Colonna married Lucrezia Gara Franciotti Della Rovere, the niece of pope Julius II. The Colonna"s alliance to the Habsburg power, likely protected the palace from looting during the Sack of Rome (1527).
Starting with Filippo Colonna (1578–1639) many changes have refurbished and create a unitary complex around a central garden. Architects including Girolamo Rainaldi and Paolo Marucelli labored on specific projects. Only in the 17th and 18th centuries were the main facades completed. Much of this design was completed by Antonio del Grande (including the grand gallery), and Girolamo Fontana (decoration of gallery). In the 18th century, the long low facade designed by Nicola Michetti with later additions by Paolo Posi with taller corner blocks (facing Piazza Apostoli) was constructed recalls earlier structures resembling a fortification.
The main gallery (completed 1703) and the masterful Colonna art collection was acquired after 1650 by both the cardinal Girolamo I Colonna and his nephew the Connestabile Lorenzo Onofrio Colonna and includes works by Lorenzo Monaco, Domenico Ghirlandaio, Palma the Elder, Salviati, Bronzino, Tintoretto, Pietro da Cortona, Annibale Carracci (painting of The Beaneater), Guercino, Francesco Albani, Muziano and Guido Reni. Ceiling frescoes by Filippo Gherardi, Giovanni Coli, Sebastiano Ricci, and Giuseppe Bartolomeo Chiari celebrate the role of Marcantonio II Colonna in the battle of Lepanto (1571). The gallery is open to the public on Saturday mornings.
The older wing of the complex known as the Princess Isabelle"s apartments, but once housing Martin V"s library and palace, contains frescoes by Pinturicchio, Antonio Tempesta, Crescenzio Onofri, Giacinto Gimignani, and Carlo Cesi. It contains a collection of landscapes and genre scenes by painters like Gaspard Dughet, Caspar Van Wittel (Vanvitelli), and Jan Brueghel the Elder.
Along with the possessions of the Doria-Pamphilij and Pallavacini-Rospigliosi families, this is one of the largest private art collections in Rome.