It is time for the legacy financial infrastructure to seamlessly connect with modern, decentralized infrastructure. Although it is increasingly evident that decentralized infrastructure for finance (namely distributed ledgers) will coexist with and complement legacy infrastructure, it is also clear that such interoperability efforts carry new risks and concerns. In particular, managing the range of heterogeneous (and not well-established) infrastructure brings security, privacy, and regulatory issues. The first step to overcome some of these challenges is to recognize that in many deployment instances using distributed ledgers, the purpose of the ledger is to share resources among the community members. The second step after recognizing that borders exist is to understand that interoperability across systems can be best achieved through the use of standardized service interfaces (or application programming interfaces (API)). In this paper we use the term ledger gateways (or simply gateways) to denote the computer and software systems that implement the standardized service interfaces into a distributed ledger. The main purpose of a gateway is to communicate with other peer gateways that implement the same standardized service interface. Among others, peer gateways perform the transfer of data and value across borders (legal or national borders). Gateways also become a mechanism to manage a permissioned environment, where abiding by laws and regulations is crucial for business compliance (e.g., EU General Data Protection Regulations (GDPR), EU MiCa regulation on digital assets, FAFT Recommendation 15, ISO 27001.