English: The Ahilyeshwar Shivalaya, also referred to as Ahilyeshwar Mahadev Temple or Ahilya Devi Mandir, is a 19th-century Hindu temple located inside the fort.

The temple illustrates the Maratha style of Hindu architecture that emerged with the collapse of the Mughal Empire. It has elaborate arched openings, windows, and doorways in a multi-storeyed structure overlooking the Narmada river. The notable structures include the ornate chhatris, the Nagara-style shikharas fused with Maratha-Rajput style lookout mandapas. On either side of the garbhagriha (sanctum), there are spiraling stairs that go to the temple's upper level. Outside is a Maratha-style Deepasthamba for festive days.

The temple has many sculptures, intricate panels with Hindu arts. The temple is dedicated to Shiva, and features a Nandi inside the sabhamandapa. Yet, like major Hindu temples all over India, the temple includes Vishnu and Devi tradition artwork. For example, the Dasavatara of Vishnu are carved on the pillars. Near the sanctum are Ganesha on the right, and Devi on the left. Additionally, the temple includes statues of Rama, Sita and Hanuman.

The temple entrance has a 16-line inscription which helps date the temple. This inscription states that Maharani Krishnabai built the temple in honor of Punyashlok Ahilyabai Holkar at the request of Maharaja Yashwantrao Holkar. The temple's construction began in 1856, and was complete in 1890.

Background: Maheshwar is an ancient town and pilgrimage site on the northern bank of Narmada river in Madhya Pradesh, India. Its fame and growth is in part from being one of the places near where two mountain ranges meet (Vindhyas and Satpura), where traders and travelers crossed Narmada river in their journeys between cities of north and south India. The site is mentioned in early Buddhist, Hindu and Jain texts, but with different names such as Mahishmati, Agnitirtha and Kalagnirudrakshetra. Though generally accepted to be the same site, there has been some scholarly disagreement whether ancient Mahismati site on Narmada mentioned in Buddhist texts is same as Maheshwar. It is mentioned in Ramayana, Mahabharata, Puranas, and by Chinese pilgrim Hiuen TSang in records found in China.

Archaeological excavations have found Buddhist stupas and caves near Maheshwar. The more famous of these are the Bagh Caves to the west, and the less known and partially excavated Buddhist stupas site of Kasrawad about 10 kilometers to the south. Maheshwar has been a profuse source of antiquarian remains and epigraphical records dated from Maurya Empire era through the Mughal Emperor Akbar. Coins from numerous dynasties, near and far from Maheshwar, including from the Gupta Empire era have been found near Maheswar. The town also finds mention in hagiographies of Adi Shankara, who met Mandanamisra and defeated him in a philosophical debate here. Its importance to the Vedanta school and the Shaiva tradition may have led to the name Maheshwar.

The modern town of Maheshwar is one of the major Hindu pilgrimage sites along the Narmada river. It has many temples, a fort and legacy monuments of the famous Holkar era Hindu queen Ahilya Bai. Maheshwar was her capital, and she rebuilt many of the most sacred Hindu temples in India including in Kashi (Varanasi).