Isla Umbú: iglesia de San Atanasio y Museo Histórico Coronel Pedro Hermosa

Isla Umbú lies about 12 km from Pilar and has the feel of a village that time forgot: streets of natural grass, little traffic and more motorbikes, horses and carts than cars. It is known as the dairy basin of Ñeembucú, and its name refers to the ombú trees once common here and to the marshes that surround it like an island. The heart of the village is the church of San Atanasio, a colonial-style building with thick adobe walls, a roof of karanda'y palm, tacuarilla cane and tiles, a brick floor and a loft used as a choir. St Athanasius sits at the centre of the wooden main altar, and the national coat of arms is carved above the altarpiece next to a crucified Christ. Beside it stands the old cabildo, built of wood and cane woven with rawhide and mud, which served as an army barracks during the war and is now the Colonel Pedro Hermosa Historical Museum. The museum gathers everyday objects (a hollowed tajy trunk used as a water vessel, parish vestments, sewing machines, ballot boxes, coins), photos of Chaco War veterans and a room on the Triple Alliance War with weapon remains and cannonballs found in the rural districts of Tajy and Boquerón. Near the centre there is also a clear-water lagoon, Laguna Capilla, popular in summer.

Residents take 8 August 1860 as the date the village was reorganised, although as early as 1785 governor Pedro de Melo de Portugal had ordered settlement of the strip between Villa del Pilar and Curupayty. The original church began to be raised two years after that reorganisation. According to oral tradition, on 2 May 1866, before the Battle of Estero Bellaco, Marshal López promised to make St Athanasius patron of the first church completed after the fight; it was the one at Isla Umbú. The structure was restored in 1970 and the old buildings were declared national historical and cultural heritage; the museum was reopened in 2003 with objects donated by local families.