Borobudur Temple is a Buddhist temple situated in Borobudur, Magelang, Central Java, Indonesia. The temple is positioned roughly 100 km southwest of Semarang, 86 km west of Surakarta, and 40 km northwest of Yogyakarta. Constructed by adherents of the Mahayana Buddhist religion during the reign of the Syailendra dynasty in the 9th century AD, the temple features several stupas. Borobudur is recognized as the biggest Buddhist temple or shrine globally and one of the largest Buddhist monuments worldwide.

Prambanan Temple is a Hindu temple complex situated in the Special Region of Yogyakarta, which is in southern Java, Indonesia. It was built in the 9th century and is devoted to the Trimūrti, which is an expression of God in the forms of the Creator (Brahma), the Preserver (Vishnu), and the Destroyer (Shiva). The temple complex is situated approximately 17 kilometres (11 mi) to the northeast of Yogyakarta city on the border between Central Java and Yogyakarta provinces.

The temple complex, which is a UNESCO World Heritage Site, is the largest Hindu temple site in Indonesia and the second largest in Southeast Asia after Angkor Wat. It is characterized by its tall and pointed architecture, which is typical of Hindu architecture. The towering central building is 47 metres (154 ft) high and is located within a vast complex of individual temples. Originally, the Prambanan temple complex comprised 240 temple structures, which represented the magnificence of ancient Java’s Hindu art and architecture. It is also considered a masterpiece of the classical period in Indonesia. Prambanan is a popular tourist attraction that draws visitors from all over the world.

Ratu Boko is located around 3 km to the south of Prambanan, situated on top of a hill that is about 195.97 m above sea level. It is not a temple but the remains of a palace. Often referred to as Kraton Ratu Boko, legend has it that it was once the palace of Ratu Boko, the father of Lara Jonggrang. Ratu Boko was built in the 8th century AD by the Buddhist Syailendra Dynasty, but it was later taken over by the Hindu Mataram kings, resulting in the place being filled with both Hindu and Buddhist references.

A stele called Prasasti Abhayagiriwihara was found in Ratu Boko, dated back to 792 AD. The stele mentioned Raja Tejapurnama Panangkarana, who is another name for Rakai Panangkaran. Tejapurnama Panangkaran ordered the construction of Abhayagiriwihara, and the same name appears in the Kalasan Stele (779 AD), Mantyasih Stele (907 AD), and Wanua Tengah III Stele (908 AD). Abhaya means peaceful, and giri means hill or mountain, so Abhayagiriwihara means a monastery built on a hill of peace. During the reign of Rakai Walaing Pu Kombayoni (898-908 AD), Abhayagiriwihara was renamed Kraton Walaing.

The Museum Sandi, located in Kotabaru, Gondokusuman District, Yogyakarta, is an operational entity that falls under the National Cyber and Crypto Agency (Badan Siber dan Sandi Negara (BSSN)). Its primary purpose is to assist the BSSN in advancing information security culture through public education and preserving the historical legacy of cryptology personnel, which is a crucial part of Indonesia’s fight for independence. Visitors have the opportunity to learn basic coding skills and explore the inception of the secret news security institution, established on April 4, 1946, during the early stages of Indonesia’s independence by Dr. Roebiono Kertopati, also known as the Father of Indonesian Cryptology.

Rumah Sandi is located in Dukuh Hamlet, Purwoharjo Village, Samigaluh District, Kulon Progo Regency. The house consists of two buildings, namely the front and rear buildings. The front building was built in 1970, while the rear building is an old building that was previously used as a cryptography house. In the National Cryptography House, visitors can enjoy a cool atmosphere and a beautiful view of the Menoreh hill scenery.